Display 21.5-inch display
1920x1080 resolution
21.5-inch Retina 4K display
4096x2304 resolution
27-inch Retina 5K display
5120x2880 resolution
Processor

Dual-core or quad-core
Intel Core i5

Quad-core Intel Core i5

Quad-core Intel Core i5

Memory

8GB

8GB

8GB

Storage

1TB hard drive

1TB hard drive 1TB or 2TB Fusion Drive
Graphics Intel HD Graphics 6000 or
Intel Iris Pro Graphics 6200
Intel Iris Pro Graphics 6200 AMD Radeon R9 M380, M390 or M395 with 2GB GDDR5
Wireless

802.11ac Wi-Fi
Bluetooth 4.0

802.11ac Wi-Fi Bluetooth 4.0

802.11ac Wi-Fi Bluetooth 4.0

Connections and Expansion

Two Thunderbolt 2 ports
Four USB 3 ports SDXC card slot

Two Thunderbolt 2 ports
Four USB 3 ports SDXC card slot

Two Thunderbolt 2 ports
Four USB 3 ports SDXC card slot

Camera

FaceTime HD camera

FaceTime HD camera

FaceTime HD camera

Keyboard and mouse

Magic Keyboard
Magic Mouse 2

Magic Keyboard Magic Mouse 2

Magic Keyboard Magic Mouse 2