yes there is a difference. I may be mistaken about this, but I believe Limewire is capable of a push. This means that people behind firewalls can send stuff to people, except other people behind firewalls. If you cant get something from behind a firewall, chances are you're behind one yourself, so don't get all worked up.

That said, since I am not entirely sure, I'm asking those in the know: does LimeWire do push?