What are all the differences between the final "2020" 27-Inch Aluminum iMac models and their "2019" predecessors?

Please note that there are no 21.5-Inch "2020" iMac models. All of these iMac models have been discontinued, but this Q&A has been updated subsequently and remains quite useful for anyone buying or selling one of these systems on the used market.

Although 27-Inch iMac models from both lines look practically identical, there are some important external and internal differences between the "2020" iMac models and the "2019" iMac models that came before them.

As documented by EveryMac.com, the "2019" iMac models are the essentially entry-level iMac "Core i3" 3.6 21.5" 4K; mid-range iMac "Core i5" 3.0 21.5" 4K and "Core i7" 3.2 21.5" 4K; and high-end iMac "Core i5" 3.0 27" 5K, "Core i5" 3.1 27" 5K, "Core i5" 3.7 27" 5K, and "Core i9" 3.6 27" 5K.

The "2020" iMac models -- all with 27" displays -- are the stock iMac "Core i5" 3.1 27" (5K), "Core i5" 3.3 27" (5K), and "Core i7" 3.8 27" (5K) and the configure-to-order iMac "Core i9" 3.6 27" (5K), "Core i7" 3.8 27" (5K; 5700/XT), and "Core i9" 3.6 27" (5K; 5700/XT).

Photo Credit: Apple, Inc. (27" iMac 5K Models)

Because some of the most notable differences are internal, a detailed comparison can be particularly helpful. A greater understanding of the similarities between the lines can be useful, also.

External Differences

All of the 21.5-Inch and 27-Inch "2019" and 27-Inch "2020" iMac models use essentially the same all aluminum case design that tapers sharply to a 5 mm edge at the sides of the display and all have an integrated webcam in the upper display bezel, speakers integrated at the bottom edge of the display, and integrated microphones.

However, the 27-Inch "2020" iMac models have a higher quality 1080p webcam (earlier models are 720p) and a studio-quality three-mic array (instead of dual microphones).

The 21.5" 4K "Mid-2017" and "2019" iMac models have a 21.5" 4096x2304 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 4K" display and the 27" 5K "2019" iMac models have a 27" LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 5K" display with a gigantic 5120x2880 resolution. Both display sizes support a wide color gamut of "one billion colors" and have a brightness rating of 500 nits.

The 27-Inch "2020" iMac models have a display with otherwise identical specs to the 27-Inch "2019" models they replace but add True Tone technology. True Tone evaluates the color temperature and ambient brightness of your surroundings and dynamically adjusts the display's white balance to match.

All of these models have a basic anti-glare coating by default, but for an extra US$500, at the time of system purchase, Apple also offered the 27-Inch "2020" iMac with a "nano-texture glass" display surface to more dramatically reduce glare.

Connectivity Differences

There are some notable connectivity differences between the "2019" and "2020" iMac models.

All of these models from both years have two Thunderbolt 3 (USB-C) ports, four USB 3.0 (USB-A) ports, one Gigabit Ethernet port (10/100/1000Base-T), an SDXC-capable SD card slot, a 3.5 mm analog headphone jack, and 802.11ac Wi-Fi.

However, the "2020" iMac models have Bluetooth 5.0 (earlier models just support Bluetooth 4.2) and have the option of 10-Gigabit Ethernet at the time of purchase as a US$100 upgrade.

Using a Thunderbolt 3 port, the "2020" iMac models also can simultaneously support the internal display at full native resolution and up to one 6016x3384 (6K) external display at 60 Hz whereas the earlier "2019" models can simultaneously support the internal display at full native resolution and up to one 5120x2880 (5K) external display at 60 Hz.

Identification Differences

The "2019" and "2020" iMac models of the same display size share Model Numbers. Specifically, the "2019" iMac models with 21.5" and 27" displays are A2116 and A2115, respectively. The "2020" iMac models also use the A2115 model number.

However, these systems can be more precisely differentiated by Model Identifier in software and EMC Number externally. Just as the site has done for other Macs for more than two decades, EveryMac.com has carefully hand documented these details from the hardware itself for your convenience:

Tapered Edge iMac	Subfamily	Model ID	EMC No.
"Core i3" 3.6 21.5"	2019, 4K	iMac19,2	3195
"Core i5" 3.0 21.5"	2019, 4K	iMac19,2	3195
"Core i7" 3.2 21.5"	2019, 4K	iMac19,2	3195
"Core i5" 3.0 27"	2019, 5K	iMac19,1	3194
"Core i5" 3.1 27"	2019, 5K	iMac19,1	3194
"Core i5" 3.7 27"	2019, 5K	iMac19,1	3194
"Core i9" 3.6 27"	2019, 5K	iMac19,1	3194
"Core i5" 3.1 27"	2020, 5K	iMac20,1	3442
"Core i5" 3.3 27"	2020, 5K	iMac20,1	3442
"Core i7" 3.8 27"	2020, 5K	iMac20,1	3442
"Core i9" 3.6 27"	2020, 5K	iMac20,1	3442
"Core i7" 3.8 27" (XT)	2020, 5K	iMac20,2	3442
"Core i9" 3.6 27" (XT)	2020, 5K	iMac20,2	3442

Additionally, EveryMac.com's Ultimate Mac Lookup feature also can identify these iMac models by their serial numbers.

Internal Differences

Internally, the "2020" iMac models are a significant upgrade from the "2019" line.

The "2019" iMac models use 8th and 9th Gen "Coffee Lake" architectures whereas the "2020" iMac models use 10th Generation "Comet Lake" architectures and have more advanced AMD Radeon Pro graphics with faster dedicated memory. The entry-level "2019" iMac models use slower system memory, as well.

The 21.5" models in both lines have RAM that can be upgraded, albeit with great difficulty, whereas the 27" models in both lines offer RAM upgrades via a convenient door on the rear of the system. Processors can be upgraded in all of these models, but the earlier "2019" iMac models have storage that also can be upgraded whereas most "2020" iMac models, unfortunately, use onboard storage that cannot be upgraded.

Accessing the processor or storage in any of these models is needlessly complicated and requires effectively a complete disassembly of the computer.

"2019" & "2020" iMac Comparison Chart

The major differences between the 21.5-Inch 4K and 27-Inch 5K "2019" and 27-Inch 5K "2020" Aluminum iMac models are summarized below. Please refer to the specs page for the model of interest for complete details:

	4K 2019 (i3)	4K 2019	5K 2019	5K 2020
Intro Date:	Mar 2019	Mar 2019	Mar 2019	Aug 2020
Disc Date:	Apr 2021	Apr 2021	Aug 2020	Mar 2022
Processor Speed:	3.6 GHz*	3.0 GHz*	3.0 GHz 3.1 GHz 3.7 GHz**	3.1 GHz 3.3 GHz 3.8 GHz***
Processor Type:	4 Core i3*	6 Core i5*	4 Core i5**	6 Core i5 8 Core i7***
Processor Family:	Coffee Lake	Coffee Lake	Coffee Lake	Comet Lake
Processor Generation:	8th Gen	8th Gen	8th/9th Gen	10th Gen
Processor Mounting:	LGA 1151	LGA 1151	LGA 1151	LGA 1151
RAM Type:	2400 MHz PC4-19200	2666 MHz PC4-21300	2666 MHz PC4-21300	2666 MHz PC4-21300
Standard RAM:	8 GB	8 GB	8 GB	8 GB
Maximum RAM:	32 GB	32 GB	128 GB†	128 GB
RAM Slots:	2	2	4	4
RAM Upgrade:	Difficult	Difficult	Easy (Door)	Easy (Door)
Standard Storage:	Hard Drive††	Fusion Drive††	Fusion Drive	SSD
PCIe SSD Connector:	No††	Yes	Yes	No‡
Standard Graphics:	Radeon Pro 555X	Radeon Pro 560X♦	Radeon Pro 570X 575X 580X♦	Radeon Pro 5300 5500 XT◇
Std. VRAM:	2 GB	2, 4 GB	4, 8 GB	4, 8 GB
VRAM Type:	GDDR5	GDDR5	GDDR5	GDDR6
Display Size:	21.5-Inch	21.5-Inch	27-Inch	27-Inch
Display Resolution:	4096x2304	4096x2304	5120x2880	5120x2880
True Tone:	No	No	No	Yes
Ext. Display:	5K	5K	5K	6K
Webcam:	720p	720p	720p	1080p
Mics:	2	2	2	3
Bluetooth:	4.2	4.2	4.2	5.0
Order Number (US):	MRT32LL/A	MRT42LL/A	MRQY2LL/A MRR02LL/A MRR12LL/A	MXWT2LL/A MXWU2LL/A MXWV2LL/A
EMC Number:	3195	3195	3194	3442
Model Identifier:	iMac19,2	iMac19,2	iMac19,1	iMac20,1◇
Original Price (US):	US$1299	US$1499	US$1799 US$1999 US$2299	US$1799 US$1999 US$2299
Original Price (UK):	£1249	£1449	£1749 £1949 £2249	£1799 £1999 £2299
Original Price (CA):	C$1699	C$1949	C$2399 C$2649 C$3079	C$2399 C$2649 C$3079
Original Price (AU):	A$1999	A$2299	A$2799 A$3099 A$3549	A$2799 A$3099 A$3549

* By custom configuration, the iMac "Core i3" 3.6 21.5" 4K and "Core i5" 3.0 21.5" 4K could be equipped with a six core 3.2 GHz Core i7 (I7-8700) processor for an extra US$300 or US$200, respectively. EveryMac.com also has documented this custom configuration as its own model, too.

** The iMac "Core i5" 3.1 27" 5K and "Core i5" 3.7 27" 5K could be custom configured with a 3.6 GHz Eight Core "Core i9" processor (I9-9900K) for an extra US$500 or US$400, respectively. It has a Turbo Boost of 5.0 GHz. EveryMac.com also has documented this custom configuration as its own model, also.

*** By custom configuration, the iMac "Core i5" 3.3 27" (5K), and "Core i7" 3.8 27" (5K) could be configured with a 3.6 GHz 10-Core "Core i9" processor (I9-10910) for an extra US$500 or US$400, respectively. This processor has a 20 MB level 3 cache and Turbo Boost up to 5.0 GHz. EveryMac.com also has documented these custom configurations as its own model.

† Oddly, Apple formally allows up to 32 GB of RAM in the iMac "Core i5" 3.0 27" 5K and up to 64 GB of RAM in the other "2019" iMac 5K models, but site sponsor OWC has determined that all of these models actually support up to 128 GB of RAM.

†† If these models are not configured with a "Fusion" Drive or SSD at the time of purchase, the PCIe connector for the SSD is not onboard and a second drive cannot be installed later. If they are configured with a "Fusion" Drive or SSD, this connector is onboard and occupied by the SSD. On August 4, 2020, Apple started to equip these models with an SSD by default. A "Fusion" Drive option still was available.

‡ If this model was equipped with the 4 TB or 8 TB SSD option at the time of purchase (but not smaller SSDs), the flash module is mounted on an expansion board with a connector to the logic board; future storage upgrades could be possible.

♦ By custom configuration, the stock iMac "Core i5" 3.0 21.5" could be equipped with an AMD Radeon Pro Vega 20 with 4 GB of dedicated HBM2 video memory for an extra US$350. Likewise, the stock iMac "Core i5" 3.7 27" 5K could be equipped with an AMD Radeon Pro Vega 48 graphics processor with 8 GB of dedicated HBM2 video memory for an extra US$450.

◇ At the time of system purchase, this model could be upgraded to an AMD Radeon Pro 5700 with 8 GB of GDDR6 memory for an extra US$300 or an AMD Radeon Pro 5700 XT with 16 GB of GDDR6 memory for an extra US$500. If the video processor is upgraded, the system uses the iMac20,2 identifier. EveryMac.com crosslists these models as their own systems, accordingly -- the iMac "Core i7" 3.8 27" (5K; 5700/XT) and "Core i9" 3.6 27" (5K; 5700/XT).

Comparison Summary

Ultimately, the "2020" iMac models were a welcomed upgrade to the "2019" 27-Inch models they replaced with a better display, better webcam, and better mics, as well as faster performance, faster graphics performance, and superior external display support but most configurations sadly lost the internal storage that could be upgraded later.

Please also see EveryMac.com's Ultimate Mac Comparison feature to dynamically compare any iMac model to any other Mac.

New & Used iMac Purchase Options

There are many places to purchase a used "2019" or "2020" iMac. However, buying from a quality company with a solid track record in the Mac market will provide the best experience and save you money and time, too.

In the US, site sponsor Adorama sells new iMac models with free shipping. Other World Computing and JemJem sell used and refurb iMac models at bargain prices with free shipping, as well. Finally, if you need to sell an iMac, A+ BBB-rated Cash for Your Mac will buy your older iMac with an instant quote and prompt payment.

In the UK, site sponsor Hoxton Macs sells used iMac models with a one-year warranty and free next day delivery throughout the UK. Delivery across Europe also is available starting at just £9.99 for two-day delivery to France and Germany.

In Australia, site sponsor Mac City likewise has a variety of used iMac models sold at low prices and available with a free warranty and fast shipping across Australia.