Why is my late 2015 21.5 non-retina 16,2 and not 16,1

[Aston441]

I bought a cheap late 2015 iMac off eBay. I expected the non-retina screen, and that is what it has. However SysInfo says it is a 16,2 and not 16,1.

Apple says 16,2 is supposed to be retina screen.

Why does the machine say it is a 16,2 when it is supposed to be a 16,1?

 

[Aston441]

Nevermind. To answer my own question:

Differences Between Late 2015 iMac Retina 4K/5K Models: EveryMac.com

Compares and contrasts all differences between the Late 2015 iMac 21.5-inch, iMac 21.5-inch Retina 4K, and iMac 27-Inch Retina 5K models. Displays, specs, and more.

everymac.com

Apples model numbers are clear as mud.