how about u和what about u有何区别?

要看具体上下文语境和情景.
无上下文的情况下可以粗略的认为是一致的意思.
但是如果有上下文的情况下：
how about的意思可以细化为如下
What is your thought,feeling,or desire concerning.
e.g.How about a cup of tea?or How about joining us for lunch?
It is also put as how about it,as in How about it?Do you want to come along?
what about的意思可以细化为如下
Would you like,as in What about another beer?or What about a game of bridge?
What do you think of,as in So what about renting that white house on the corner?
Why,concerning what,as in I need your frank opinion.What about?
what about it?What should we do,what course of action should be taken.For example,We're supposed to be there at noon and bring two sandwiches eachnow what about it?
Good luck!