Yeah, they are almost the same. If I say What's Up I don't expect as big of a response. I can walk buy someone and say What's Up, as a greeting instead of hello. If I say What's New, then I expect a conversation about what is going on in that person's life.

Nino's comments are very good. I would also add that "what's new" is appropriate to say to anyone, where as "what's up" is more casual and should be used with friends, but is not appropriate for a work setting.

"whats up " usually is said to assess someones mood, like when people look sad. "whats new" is more to do with their circumstances like news...

good answer nino

they are pretty much the same thing. its very common for people to say whats up as a greeting to friends. you can also use "whats new?" as a conversation starter. for example, "hi, how are you?" "good" "whats new?"