Can anyone explain what the difference is between Street Photography and Travel Photography?
Travel photography can encompass street photography but it may also include many other types of photography as well: landscapes, architectural, environmental portraits that go beyond a street scene, wildlife, indoor scenes at tourist attractions, museums, or historical locations, etc.
Street photography ∈ Travel photography (at least I understand it this way).
Travel photography is about landscapes, people, architecture, air shots, nature, animal, all aspects of travel. Street photography is part of it.
Street photography is more about shooting daily life situations, showing the expression and real atmosphere of city, place you're living/visiting. It's more about capturing moments than places.
I think that the best place to get inspire when it comes to travel and street photography is Photler.com - go to http://photler.com/inspire, browse some of their hand-picked galleries and you'll quickly get the difference :-)