how about&what about
How about you? What about you? I 'd like some ice cream,how about you?/ what about you?
Please telll me the difference about how about and what about.

Question

how about&what about
How about you? What about you?  I 'd like some ice cream,how about you?/ what about you? 
Please telll me the difference about how about and what about.

Answer

1. 'How about..?' and 'What about..?' can be used interchangeably when you are making a suggestion:

What should we have for dinner?  How about pizza?
What should we have for dinner?  What about pizza?

Additionally, 'What about...?' can be used in the sense of 'Wait a moment, haven't you forgotten ...?' :

2. 'Then we can all walk down to the beach for a picnic.'
'What about grandma? She can't walk that far.'
'Oh, of course. Silly me. Well, let's go to a restaurant instead.'

You can't use 'How about..?' in this sense.

Answer

In English spoken language people use the terms - perhaps incorrectly - interchangeably.