Quoting Gone 12345....:" there's no other possibility they could be anything else? I don't really know much about twins lol"
i'm not a doctor, my only qualification is having gone through a twin pregnancy myself
that said, mine are identical, and my pregnancy was high risk, so i went to an ultrasound every other week the whole time. i'm also a statistician by education, so i researched all about the odds of twins.
based on everything i've seen, chances are overwhelming that they are fraternal
it's like this.
without seeing any ultrasound at all, fraternal twins are three times more common than identical ones, so i'd bet $100 on fraternal
IF they were identical, odds would be 75% of a shared chorion. you have a very thick, very apparent area between the two babies. this strongly suggests fraternal. only 25% of identical pregnancies are diamniotic (which MIGHT look like that. but i think your ultrasound is too thick EVEN for that).
basically, do i guarantee fraternal? no. would i place $1,000 on a bet that they're fraternal? absolutely.