The Atari ST computers are not known for their great keyboards. The built-in keyboards in the Atari 520ST, 1040ST and Falcon030 all use rather “fat” keys and the key action is also considered mushy.
When Atari introduced the Mega ST series in 1987, the computers had an improved external keyboard. Although it still has the fat keys, the key action was improved with the use of cherry keyswitches. You can identify this external keyboard because it still has the rhomboid function keys at the top. My Dad had a Mega ST2 and I remember its keyboard the great feel of its keyboard.
The external keyboard uses a telephone-style connector to connect to the computer, unlike the large, round DIN-style plug used by IBM keyboards. The two joystick/mouse ports are also on the keyboard itself (technically underneath it, making them a little hard to reach) rather than on the computer.
The Atari TT030 and Mega STe also have an external keyboard and it was slightly different than the Mega ST keyboard. Other than the colors (TT was white, Mega STe was gray), these newer keyboards were identical to each other and also improved in several ways.