No, they don't have the same kind of leaf...at least if you are talking about Persea americana (avocado) and Mangifera indica (common mango), the leaves are quite different. If you google image each of the two names, followed by the word leaf, you should be able to easily see the difference.

BTW, the reason your post hasn't received answers is because you put it in an obscure sub-forum meant for images. Few GardenWeb users read this forum.