I do think they look somewhat similiar,but Leo is like chubby(well he isn't but like grown up, fuller face) and Michael is like too grunge and the long hair so the comparison is smaller and their similarities too.
I think Dicaprio is a good actor, check what's eating Gilbert Grape(he was absolutely fantastic) but then he comes round doing crap.Pitt is always good, or at least in the films I've seen(dreamers,last days,murder by numbers).
Leo in Titanic and Michael in Silk look pretty much alike.