which does what? i.e what muscles

are u kidding?

if not, biceps

no lmao I know what it does but theres a difference between biceps and arm curls arent there - hammer curls is thum up

which does what? i.e what muscles

Both exercises work the biceps and to a lesser extent the forearms (through static contraction) but the hammer curls also work the brachialis - an oval shaped muscle that you can see between the biceps and triceps when looking at the arm side-on (look at a pic of a bodybuilder and you'll see what I mean)

ah right kl good k