Zombie Clarification

I need something clarified for me. I have been racking my brain trying to figure out the answer and have gotten nowhere.

Zombies vs Mutant Zombies? What's the difference? I mean, aren't zombies considered mutants anyways? After all zombies eat human flesh and are dead to begin with. Wouldn't that make them mutant? If there is a difference between your regular-run-of-the-mill zombie and a mutant zombie, then please share. Seriously, if I were to suddenly perish and not know this answer then I would have to come an haunt you until I was answered satisfactory. And trust me, I'd be a terrible ghost to haunt you. I'm told I snore and I am a terrible grumpy bitch in the morning. Plus, as a ghost I wouldn't be able to have my beloved diet coke. It wouldn't be pretty. It would greatly behoove you to just answer my question and skip the whole haunting part. I'm only looking out for your best interest here. That's how much I love you.