Yeah, there is the main universe referred to as Earth 616, which embodies everything from spidey to cap, continuous story from the 60s to modern day (comics wise). Ultimate comics are an alternate reality with different takes on everything, but the same underlying base. However, these two universes exist in the same.... well, universe. There are reference in rare issues with multi universe crossing of each other, for example in the Squadron Supreme Ult. issues, some of them seem to recall Cap and say 'we've met, you're the avengers' with Cap confused, telling him that they're the ultimates. I'm paraphrasing, so that may be off a bit but you get my point.so is "ultimate" just an alternate reality for the marvel universe? can any one universe be considered the definitive one? and i'm guessing the MCU just takes from wherever it feels necessary?
The movies serve as a free for all where there are elements being grabbed from both lines, as well as totally new stuff of course.