I'll take a crack at it...
Both style turrets use 1/4 MOA movements. The target turret doesn't mark every MOA with a number while the M1 does.
See pic
M1 turret has larger diameter top with bumpy knobs. The M1 doesn't have a cover while the target turrets do.
First pic with M1 turret, second pic with target turret with cap installed
I saw no one had answered this...then I post to find I am a bit late.
Anyway you now have plenty of pictures and explanations.