The AI is definitely easier. Try fighting Akira at level 8 in 5 then try it in 5U. Level 8 in 5 meant hardcore turtling with CONSTANT holds and throws and strikes right whenever he can punish with follow up hard-hitting juggles. In 5U the punishment is still there with hard-hitting juggles and he turtles a lot but often leaves himself open small windows for you to smack around. Not to mention he barely ever holds. You can still chain endless throw punishes on him when he tries that slow punch when he's mid range. Hell, I even 2P'd him with Momiji about 20+ times in a row before he crouched to guard them. The only positive change he has is that he seems to use mid punches a tiny bit less.
(I know all this from using mostly just him as my training dummy and setting the AI to fight back to try stuff out)