When Bella hits Jacob in Eclipse she hurt her hand but when she hits Paul is New Moon nothing happened. What do u think about this?

It would have been too many things happening at once if Bella hurt her hand

one or the other she hit jacob harder or jacob has a hard head

She just slapped Paul which make her use not so much weight on her hand but she punshed Jacob so she used more strengh

i wondered the same thing myself at first,but seeing New Moon since then she only slapped Paul which didnt hurt her hand,but she full on punched Jacob(which he fully deserved btw for kissing her against her will),which made her sprain her hand.