The idea behind a soul golem is a rather confusing mess. Whereas the typical definition of a 'golem' would imply otherwise inanimate material animated and controlled via magical means, a soul golem can be any of a wide variety of objects controlled by a person's very soul, generally leaving little to no direct control in the hands of said soul. Said object does not necessarily need to be inanimate or animated via magic, per se. The soul is the main factor in naming it.

Why this apparent lack of consistency in naming exists is unknown. Though it is well known mages who study necromancy to that degree are an eccentric bunch, to say the least. Seriously, what else are they going to do? It's a lonely study, to be sure.