In a sense they all level you up the same. If anything the higher difficulties would level you up more. The more damage you do and the more damage you take the quicker the related offensive and defensive skills will level up.
maybe someone knows for sure, but i'm pretty sure difficulties have no bearing on how fast you level up. e.g. if you get 1 point of heavy armor exp every time you get hit for 1 point of dmg, it's the same in every difficulty.
with that said, i tend to believe that your defensive skills will suffer a bit on master difficulty because you tend to find ways to play tactically to avoid damage, such as fus ro dahing a boss to whack on him, or making better use of terrain than you would on the low difficulties just rushing in and whacking everything.
with that said, with full double enchanted daedric you can still run around whacking everything without too much effort on master difficulty so in the end it balances out.
If you level up armor skills just for taking a hit, then novice would level that up faster since you can take more hits. If it goes by damage, then it will be slower, since novice players don't receive as much damage. I think it goes by damage done, so the higher the difficulty, the faster you level.