The UE3 stuff is like 7 months old. I'm sure it looks better than that now.

I guess the main difference would be that Epic's demo actually did something. (Edit: Not that it'd be that hard to make Carmack's demo do something as well)

Carmack's demo was neat but I came away from it with the same feeling I have for most of id's games. They're neat but mostly just showcases for Carmack's tech. The more impressive stuff is usually what licensees do with it.