In interesting question if you consider politics. :) Anyway a quick reply is they are pretty much the same as far as science classifies them. Kingdom, class, family etc. The eagle 'generally speaking is larger' more specifically the head. The hawk tends to be more woodland orientated vs. eagle mountainous.
The hawk is thought to be the brains of the outfit and the eagle the brawn. When you get into there a little nuances like the Red tailed hawk is a pretty big bird. We have those here where I live. There is one that roosts on the shed at the edge of my garden a few times a month. They have both body size and wing span larger than some eagles. Also, hawk gets tossed about when generalizing birds of prey - falcon, buzzard, eagle, etc.
Don't quote me on this, but I believe here in the northern hemisphere we have more hawks than eagles. I can only think of two - bald and golden eagles in the states. Many eagles call home Asia and Africa