A PC is a personal computer as in a computer that is owned (or intended for) and used by one person. A Mac is a special brand of PC that is provided by Apple Inc.
Apple and non-Apple PCs are almost identical in terms of specs. The main differences are the OS and the mechanics, and the price tag.
This Hunch survey uses PC to mean “a PC from another supplier than Apple”, which makes the survey non-objective/non-scientifical before it even started, so read with caution..
Hunch Blog – Blog Archive – Mac vs. PC- A Hunch Rematch
What is kind of funny and also a bit disturbing is that PC and Mac (per the above definition) users still get so emotional about these things.