Generally, it is different. In home audio, the subwoofer is a discrete channel, usually with its own separate speaker wire. That's what "5.1" means. 5 discrete audio channels going to 5 full-range speakers, plus a discrete subwoofer channel.
Right, I know that. I was talking about the subwoofer itself -- a 10" free-air sub (again, in my car experience, perhaps not applicable to home environment) can sound pretty good playing a full-range (i.e., no crossover filtering) signal, and could thus be connected and run on the same signal path with smaller speakers if necessary, which in this case seems to be the case.
tanstaafl.