A CHORD WILL HAVE DIFFERENT MEANING AND A DIFFERENT PURPOSE DEPENDING ON WHAT KEY YOU'RE IN...EVEN PROGRESSIONS.
DID YOU KNOW A 7_3_6 AND A 3_6_2 IS THE SAME PROGRESSION? ALSO IF YOU PLAY THE SAME CHORDS, FOR THAT PROGRESSION...DEPENDING ON THE KEY, IT'LL HAVE A DIFFERENT SOUND / MEANING TO THE MUSIC, EVEN THOUGH IT'S THE SAME PROGRESSION?
LET'S TAKE: 'THANK YOU LORD' AS AN EXAMPLE;
DbAb / Db__THANK
CGb / BbEbGb__YOU
FEb / D_____OOOO
BbF / Bbm7___LORD
NOW THAT'S A 1__7_3_6 PROGRESSION, IN THE KEY OF Db..
WE'RE GOING TO TAKE THAT SAME PROGRESSION, AND TURN IT INTO A 3_6_2 USING THE SAME CHORDS, FOR ANOTHER SONG..IN Ab...3_6_2 IS LIKE A VAMP, OR REPEATING OF A PART OF A SONG, USUALLY THE ENDING:
BbF / Bbm7__GLO
CAb / Ab__RY
DBb / CDFAb__TO
EbAb / Db6__HIS
CGb / BbEbGb___NA
FEb / D_____AA
BbF / Bbm7___ME
GbE / BbDbEAb, (Dbm6) LEAD-IN CHORD TO THE BbF / Bbm7 TO PLAY OVER AGAIN...THAT'S A 2_3_b5_5_3_6_2
THAT VAMP IS PLAYED OFTEN, YOU HEAR IT ALL THE TIME!