The guy in Fallout 3 that worships the atomic bomb in Megaton. I am pretty certain it is the same voice actor too?

Nah. I don't know it for a fact, but I'd bet money that it isn't the same voice actor. The difference is, is that Talos is real, and some what? "Atom god." Is obviously not real.

They're both loons though.

Hagrid, the atom god was real for those ppl. In fact, when I blew it up, they were all singing praise~ lol.

The only difference between the two (For me) is that I like Heimskr.

Yep. And from what I heard, TALOS is actually an organization from the 9E.