Marvel doesn't do reboots.
All their characters have their historys intact for the most part. Occasional retcon aside, or individual reboot.(one more day)
They have a "sliding" timeline. one year passes for ever 5 or something like that. Its not exact.
Tony Stark for example, started in Vietnam, then Korea, then I forget, and now Afganistan.
The xmen were teenagers in 1960, and are 23-30 now in 2013. They have actually aged. but only 10 years or so, over 50.
10 years seems about right for most. peter started as 16, he was 28+ or so at one point, and is like 22 now I think.(one more day...)
Even the Ultimate universe.
Ultimatum was not a reboot really. It was a house cleaning. They killed off EVERYONE. well not everyone, but like 40% of their cast. The history stands though, the survivors remember that event.
Marvel numbers their universes.
Main universe is 616.
Ultimate I don't remember.
Every whatif, movie, etc occurs in its own universe.
DC reboots. and its stupid.
DC USED to have the universe numbering much like Marvel, but do to the events of infinate crisis, etc, there are no longer infinite universes. only 52.
Personally, I think that is stupid, and I like to say, those 52 were simply split off, and separated from the snowflake, which is the full multiverse, as described in Wildstorm.
52 worlds is not enough. And, despite the nu52 reboot, the Wildstorm books still exist, so their universe still exists in terms of metafiction.