The other difference is intention. To be really called a troll, your goal has to be to get a rise out of the majority of those who hold an opinion contrary to yours.
There's the rub.
In a forum like this with so many differing opinions (bull vs bear, techie vs trader, news/event-driven vs TA, etc.) it's hard for anybody not to be considered a troll by someone else.
I'm sure some people consider me a troll for posting silly bear pictures but my intention is simply to find humor in people who take themselves too seriously.
ElectricMucus obviously delights in being contrary but that's just because he's obviously a punk, and his posts are usually witty and humorous.
It's the serious self-important spammer trolls that I find most annoying.