They are the same in some, but not all, situations. 1. When you are making a suggestion, they are interchangeable: "What should we have for dinner?" "How about pizza? / What about pizza?" 2. When you want to say 'Hold on a moment, haven't you forgotten..?' only 'What about?' works. "I've got a tie for Dad, some perfume for Mum, and toys for the kids." "Hey, what about me? Don't I get a present?'

There's no difference. Both mean the same thing and they're both common. They can both be translated into Chinese with "呢".