Q: How do you learn to figure out what different chords are by ear?
A: go through about 50 of your favorite songs, and identify each chord with brute force. quickly unpause/pause (or nowadays you can edit to loop a tiny fraction of audio very quickly) and just pick it out note by note and put it together. write down all the chords to a song (in time, with bar lines, etc.)..... once you do this for about 30 or 40 songs, i think you will find that you don't have to search for the individual notes anymore. ... maybe not even pause it at all. After about 100 more songs, you probably won't even have to listen to the song, you will be able to do it from memory. after about 1000 songs, you will probably be able to hear someone singing the melody for a song you have never heard before, without hearing the chords, and figure out what the chords should be. after 10,000 songs, you should be able to play chords along with them on the first try, never having heard the song before, and have them think you already knew the song