I read on a loading screen that higher difficulties grant a higher chance to find legendary items.

But will they also have higher stats?
For example i found on normal a combat rifle with a perk that added 25% extra damage. Is it possible to find in higher difficulties weapons with a higher modifier? Or is there just a increased spawn chance for legendary mobs?

If yes the fallout endgame would remind me a bit of diablo

Edit: to be more clear i mean will the legendary effect on items be higher when a item is obtained in higher difficulties compared to lower difficulties.

yes I believe so, I haven't personally tested it but I think that is the whole point of legendary enemies.

I think it only affects legendary spawn chance. According to the guide there are a set list of modifiers from legendaries. I think the highest is double damage. Most are like 25% to something