Umm, coloration, size, lions live in "prides" which are large groups consisting of one head male and a few juvenile males and many adult females, tigers live solitary lives. Lions hunt on the savannah, tigers hunt in jungles. Tigers hunt there own food, male lions rely on the females to hunt. And MUCH more.
Lions have manes tigers have stripes
Lion are solid color and males have manes while tigers have stripes
A tiger has stripes and a lion has the thing with a lot of fur around his neck :P