So two of my friends are learning a song on guitar:
The song begins with an instrumental intro and kick right into the chorus with vocals. The chorus, which is sung and played twice, is the main issue.
One friend (A) hears: Amin, Fmaj, Dmin, Amin, Fmaj, Dmin, Gmaj, Emaj, then this progression repeats
Second Friend (B) hears: Amin, Fmaj, Gmaj, Cmaj, Amin, Fmaj, Gmaj, Emaj, then repeat.
They both sound right to me, oddly, so I suggested loading the song into Riffstation, a popular program that calculated the chords for songs. And see what it would give. The results were from Riffstation:
Amin, Fmaj, Gmaj, Cmaj, Amin, Fmaj, Gmaj, Cmaj. which is also slightly different from both.
My questions are why do both of their progressions sound correct, is it a play on the ear? or can this be explained using theory? Also, what is the true progression for the chorus.