I think in this kind of situation it would be ok to use either, the meaning would stay the same. Another example would be if some asks, "How are you?" and you say "I'm fine. What about you?/How about you?" In general though, "What about you?" is directly asking someone about their situation, whereas "How about you?" is more of a suggestion rather than a question. For example, if you wanted to suggest that Mike comes to the party, you could say "How about you come (to the party) Mike?" but you could not use "what" in that situation. Does that make sense? Hope it was helpful :)