The Ableton Push and Push2 are custom midi controllers instruments developed by Ableton to specifically work with Ableton Live. The Ableton Push (Gen 1) came out the at the same time Ableton 9 was released in March 2013. According to what was written on the back of the box that the Push came in “Push is a new instrument that solves an old problem: how to make a song from scratch. With hands-on control of of Melody and harmony, beats, sounds, and song structure, Push puts all of the fundamental elements of music making at your fingertips – and it fits in a backpack.”
The concept is how could you write electronic music on a computer without using a mouse.
Ableton furthered this concept with the release of the Push2 and Live 9.5 in Nov 2015. The Push2 has several improvements. One obvious addition is a colored screen instead of an LED screen. But the pads are more sensitive, the buttons are more recessed so it feels smoother to the touch, and the menus on the screen are just more intuitive to navigate.
Image taken from Andri Søren youtube channel.