Your left bicep wont look as full if you bring up the peak more, it looks fuller because the peak isnt as high, so on your left hand hit it harder with a lighter weight, twisting your little finger into your shoulder at the top of the movement, to really contract the peak.
Close grip barbell culls hit the inner head as you know, giving more size, but wide grip hits the outer head, to me it looks like the outer head on your left bicep isnt as developed, and possibly your inner head on the right isnt as developed as the left side.
Just a thought man, but a super physique keep it up.. hope this helps bro.
Russian