Me and my brother play on the PC and Xbox 360 respectively, we play at the same time, perks and difficulty to kind of help each other with locations, secrets and such. We have noticed that the game is easier on the 360, or more difficult on the pc and by a large margin, his master is kind of my adept (medium) difficulty. For example we did the quest to heal the tree at Witherun at the same time, when we went to kill the Hagraven (birdwoman) we had the same perks, i was lvl 9 he was lvl 10 and we had the same bow and arrows but it took me like 3 more times to kill her, for every shot i did a lot less damage than him and it took 3 fireballs for her to kill me when he could take 6. Another clear example is the fist fight you do on Whiterun's inn with the woman soldier, again same level armor and perks but he won the fight with like 30 hp left and it took me 2 bars of hp using potions to win the fight. I just did a test with the bandits outside Whiterun in master difficulty, i kill them with 4 shots, he just needs 2 to take them, same level perks and bow, yes the damage done on the 360 is higher. So is this a bug or is intended? My brother doesn't like it, he enjoys a challenge as much as i do, but he will not get it on the 360 like this.

Did you take into consideration the level of your combat skill and the damage on the weapon? Just because it's the same bow type doesn't mean it's doing the same damage. A daedric sword can do anywhere from 30 damage to as high as 500 damage, for example.

Short answer: You're eyeballing.

I'm not saying you're wrong, I'm just saying your testing is inconclusive.

I agree with this. With the hagraven fireball thing, are you the same race? The 3 versus 6 that he took sounds like he's a dark elf and you're not.

Yes i took that into consideration and yes we are the same race wood elf, i repeat we had exactly the same perks. I started a new character in both versions, same everything, i confirm, is easier on the 360. If any of you have access to both version please confirm this, i may have a bug on installation or something like that.

Maybe your brother has more luck, such as the critical strike perk with a bow. Sometimes a fight could be more or less difficult depending on many things, enemy stats ans stuff, what he uses to defend himself, spells he casts etc.
After i die, i am often surprised to crush my enemies with more ease than the first attempt.
Perhaps your bother's race is better at firing arrows than yours. Try to test with magic, as damages are not fluctuating so much.

They have identical characters, race and skills.

I've observed the same thing as well. The AI doesn't do the exact same thing each time you go through the same fight.

I play Skyrim both on the PC (for mods) and the Xbox (so I can play in bed) and I haven't noticed a difficulty difference other than I'm better with a mouse than a thumbstick.

A better test would be for both players to save right before the same difficult fight - and relaod the same fight multiple times to see if it's consistantly easier for one. But a single fight where it took one player more hits to kill the mob than another player, doesn't really mean anything.

Aren't there set levels when the enemies in an area will be higher based upon the player's level?

As at level 19 I was kicking ass with a mage, then hit level 20 and suddenly the same type of enemy becomes more challenging.

how 'bout this:

Start a new game on both platforms, same race, same weapon, and do an exact test on the first couple of enemies you can. Or maybe after you exit the first dungeon so you don't have your friend interfering in the fights.

The game may randomly load enemies within a certain level range, so you're getting a hag raven a couple levels above or below what you're brother's getting. Regardless, this doesn't seem too important or game breaking.

I think this has a lot more to do with it than either version being different from the other. How the AI handles the fight will have huge impact on the outcome. I've fought Elder Dragons that were very docile, and turned over and easy soul, and then i've fought Frost Dragons that are extremely active and give me a serious challenge.

Maybe he had walked into the dungeon before? I recall it being said that the game "locks in" the level of mobs in a dungeon when you first enter it, so that if it's too difficult you can come back a bit later and pretty much clean up. If he'd entered it as a much lower level, the game would have locked them all in as that lower level.