No, Futsal is Futsal and 5-A-Side is 5-A-Side.
The differences are those Oli mentioned. About goalsize (net) I think it hasn't changed though. We have always used those small ass handball goals.
But the biggest difference is the ball types.
Futsal = Heavy balls. They roll slower.
5-A-Side = Lighter balls. They roll fast.
My team always bring our light footballs to matches and we give them to the refree, hoping that he wont notice anything.
The purpose of the new futsal is that it shud be more enjoyable watching, but it is not. Most teams just pass their targetman, he hold the ball with his feet and deliver to another guy.