Did you even look at the Wikipedia page you linked to?
Cro-Magnon man were the ancestors of modern Europeans. Besides being a bit taller, and possibly not being as light skinned/haired as modern-day Europeans, they were otherwise indistinguishable. Because they're the ancestors of modern Europeans only, and not the ancestors of, say, Africans or Asians, they are nested within
Homo sapiens.
There were, of course, other branches of human evolution - populations we're pretty sure are not our ancestors in large part. Most famously the Neandertals, although some newer evidence suggests they may of hybridized with "
Homo sapiens" to some extent. Also there are the "robust Australopithecines," Hominids who walked on two legs, were larger than our ancestors (but were still shorter than we were - at that time few Hominids broke five feet, and none broke six feet), and seem to have had a vegetarian roughage-filled diet similar to Gorillas. Also, of course there are the dwarfed human "hobbits" from Flores.
As to what the world would be like if one of them ended up on top and started civilization, there's not even really reason to conjecture. We basically have fossils and stone tools, which just tell us about biology and their level of technology (which usually wasn't much different from their contemporaries - our ancestors). We can't come to any conclusions about "behavior" from this - we certainly can't say that any one species was more aggressive than we are. Some Neandertals seem to have engaged in cannibalism, but then again, so do/did some modern humans.