Dear N:

You wrote:
> Which of these sentences is correct (with the given meaning):
> 1-Unlike John, you’ll like Harry.

This is ambiguous or misplaced at best. It literally means that you will like Harry, unlike John who does not like Harry.

> 2-You will like Harry, unlike John.

This does mean what you intend but is awkward at best. Why not say it as you have written it below?

> Meaning: You didn’t/don’t/won’t like John, but you’ll like Harry.