The Ultimate!Spiderman Dimension is more akin to our world than the Amazing!Spiderman DimensionTo me, the A!SD seems more like a retroistic dimension (the way the levels are with its grainy cel shading adds to this too) while the makers have said the U!SD is based more like modern day comics. It would also be why Kraven is based more on his older incarnation than the currently ressurected version in the mainstream Earth-616 of Marvel Comics.
The Ultimate levels are in continuity with the Ultimate Video GameBecause Parker's got to still be alive somewhere, Dammit!
By that same token, the Amazing levels are continuations of Spider-Man: The New Animated SeriesBy virtue of "Same voice actor"
And by THAT token, the Amazing world in the DS versionis in-continuity with The Spectacular Spider-Man, and presumably, Spider-Man: Edge of Time.