Just picking interest gradually from this forum but with time I could tried it out to see it was is.
Bitcointalk is the first real forum experience that some of us have had. I mean, I was on Reddit before, but not as active as I am here in the forum.
Reddit is more active than Bitcointalk, with lots of traffic to be honest, what really makes them different from Bitcointalk is that, users can't promote companies with ads just like the way Bitcointalk users does in sig promotion.