There isn't a difference. Street magic is close up magic with the wrong name. "Street Magic", until David Blaine came along, was busking. As in, setting up a show, drawing a crowd, doing your performance, and asking for tips. Then Blaine came along and called his special Street Magic - and in it he did close up magic for (largely) random people. I honestly can't remember right now if he had any 'big' names in that first special. This means that a huge number of people were introduced to the term "Street Magic" that way - and it's not correct. Much like Bryan Brushwood's "Bizarre Magic" label - it's not accurate. But it also doesn't matter, really. The differences are esoteric - only magicians care.
Tips for close up - remember that it's a conversation. An interaction. You're not performing 'at' people. You're inviting them into your reality for a little while, and hopefully showing them something really incredible. Remember that most people will never see more than one live magic performance in their life time. You have one chance, every time, to give magic a good name. Magic isn't like music - If someone hears a singer they don't like, they say, "I don't like that singer". But if they see a magician they don't like, they say, "I don't like magic."