Watching the Thor movie, another difference (probably noted only by me?) is that the Bifrost doesn't break you down into your component parts the way ST's Transporter does. The Bifrost lets you travel quickly between worlds, but you do it intact and you're aware of the trip, Vs being just a beam of energy that has to be reassembled once you get to where you're going (and HOPEFULLY get there intact and put back together the way you're suposed to be!).
So, what would happen if by a 200-Trillion-to-One accident, the two accidentally intersected each other while in use, and Star Fleet personal end up in Asgard and Asgardians end up on a Federation starship

