a Camcorder always has a 4 pin connection, whereas a PC either has a 4 or a 6 pin firewire connection. Now the easy part is if you have a Mac, then you always have a 6 pin connection on the PC. If you don't have a Mac, then you can have both a 4 and/or a 6 pin connector. The difference being a 4 pin connector isn't powered, whereas a 6 pin is powered.
Link for Firewire connector
The formal name for this protocol is IEEE-1394, Sony calls it i-link and Apple calls it Firewire