I always though supporters attend games whilst fans take interest in a team without actually going.

"Fan" is short for "fanatic" and that's the way I would interpret "true fan". But to me a supporter is pretty much the same meaning.

I have nothing at all against casual supporters, of any type, or even those disparagingly termed "glory hunters" - as if there was something somehow wrong with enjoying a sport just enough to go watch a top team in action, or even just go to (say) a Final. What on earth is wrong with that? Nobody has an obligation to be a fan, and being or not being doesn't make you a better person.

(Though I am 100% certain that rugby league fans are indeed, pound for pound, as good people as you will find, but that's another discussion)

The touble with a casual supporter is that the elastic goes in them. I tend to favour the older leather supporter myself.

Too much information