Personally, I differentiate between a zombie, and a ghoul.
To me, a zombie is an undead or a corpse given ambulatory powers. Often they are near mindless or completely mindless. They usually do not breathe, but might make verbalizations, however this is usually negligible. They often require consumption, but not sustenance per se. Usually they exhibit signs of progressive and uninterrupted decomposition, or at least they do after time passing, comparable to a corpse.
A ghoul, on the other hand, is a result of infection or at the very least a more powerfull and motivating power than simply reanimation, although again these are loose interpretations. A ghoul will exhibit emotion, but on a very primitive level, like rage, or confusion. Because most often a ghoul is not strictly 'dead', it retains ambulatory efficiency, and thus moves faster and can perform more coordinated exercises. Respiration is usually observed, as are various animalistic calls and sounds. Cannibalism is an act of sustenance. Often, if brought on by a viral infection, the act of infecting others works in tandem with the cannibalism- if prey is caught, it is eaten, but if it escapes wounded, it passes on the infection.
Again, this is just how I break it down in my head. As a D@D player, it's like the zombie is the standard D@D zombie, an ambulatory corpse, and the ghoul (to varying degrees) represents a pinnacle of hollywood fare, with degrees between them for most movies.
As to the reality of the situation, corpses can be made to spasm with electricity. If it were sustained for a purpose, and made to effect ambulation for some purpose like a temporary robot made of flesh, by my definition that could be a zombie, if sustained for a purpose. An argument against would be an argument of semantics and definitions, I guess.
Oh my! I didn't mean to go off on such a tear. Just got caught up in the subject!
