The tiger and lion do have some similarities. They both have no predators of their own and are at the top of the food chain.
However they are also very different. One of the most obvious being their appearances. The tiger has eddish-orange fur, with lighter underparts. Lions a mane of long hair (if they are male) and their "golden" fur.
Another difference is the lifespan. A tiger usually lives 10 - 12 years in the wild, and it is said they live up to 26 years in captivity. Lions however live up to 12 - 18 in the wild and can live over 24 years in captivity.
There are many more differences I could list.