he's 11? make the kid go on a coaster, at least Splash Mountain. at his age he should at least be into softer coasters. and Splash Mountain is barely a coaster, it's more of a dark ride mixed with a boat cruise with large drops every now and then. just make him get on one at his age, i guarantee you he'll have fun at this point.
anywho, yes IOA and Uni rides are considerably more intense than Disney rides, but not to the point where he won't enjoy it.
IOA:
he likes simulator rides so Spiderman is a go
Hulk is a super mega awesome coaster, so no-go
Dr. Doom is basically Tower of Terror so unless he likes that, no-go
Seuss Landing is, well, Seuss Landing
WWoHP is a great place to transition your kid to liking the rougher rides
Flight of the Hippogriff is a gentle coaster he'll like that
Forbidden Journey is... scary. and very rough but it's best to not tell him that, he'll like it
Dragon Challenge is basically a coaster, best not to let him on it until after he's been on Forbidden Journey so he can make the decision himself whether he wants to take it a step further
Lost Continent just has Poseidon's Fury which is just a show so he's fine
Jurassic Park's biggest draw is River Adventure which just has a lot of scary scenes it's not intense at all
Toon Lagoon's two biggest attractions are water coasters
Ripsaw Falls, i don't exactly recommend if he doesn't like coasters. it has slow moments but it's a coaster i won't fabricate that
Popeyes is safer, a lot tamer he'll be fine on that one
Universal:
Revenge of the Mummy is no-go
Rip Ride Rockit is no-go
Transformers might be a no-go not sure yet
the majority of attractions here are either calmer rides or shows so like Universal is, compared to IOA, the tamer park so
MIB is good
Twister and Disaster are good
Simpsons is good
Kidzone is, well, Kidzone
Despicable Me and Shrek are good
so, there's Universal Studios Orlando referenced for your children. but seriously he's 11 he needs to get over that fear.