Hello, i data mined the game.
TL;DR: At level 100, there is NO DIFFERENCE between normal and hard modes, and even while the player still has a lower level, the difference is EXTREMELY MINIMAL.

For the whole explanation, hard difficulty never touches the loot table directly. However, it adds an extra point to the threat level. Threat level is what you see as "new milestone" each time you earn enough xp. 5 player xp levels = 1 extra threat level.
Loots are determined based exclusively on this threat level which goes from 0 to 20. However, all loot tables of the game are capped at 15. So loots are EXACTLY THE SAME for all difficulties starting by character level 75 (ie. ppl playing in hard getting the maximum unique odds starting by level 70). So before reaching that level, playing in hard mode is like playing with 5 extra levels (towards the loots) compared to players in normal mode, but the difficulty increase (especially the x0.6 damages dealt) are actually not worth the loot. (I mean, its a harder difficulty lol, it just doesn't justify going in hard for better loots if you are already struggling).
I recently updated the wiki page about it, you can check on minecraft .wiki/MCD2:Difficulty for more details.

Also about your statement about Rare loot, it is possible to get rare loot from storm chests, even in normal and hard, but not at level 100. The reason you get only Rare in easy difficulty is because the game never loots Special & Unique rarity items in easy. I placed the loot table of the Storm Generators chests on minecraft .wiki/MCD2:Storm_Generator if you want to see the real odds.

EDIT: I sourced everything stated here in the official wiki in the Reference sections.

I can't believe the Internet lied to me. No wonder I wasn't getting any uniques in the dungeon on easy mode.

GOD BLESS YOU FOR FRYING YOUR ENTIRE BRAINSYSTEM FOR CHECKING THESE STATS FOR US BROTHAINGTON WE MUCH APPRECIATE THIS GUIDE W-INGTON DAY IT IS INDEED TO GRIND LOOT ✌🏼😥

From what I've seen, you can't get uniques on easy other than quest rewards, but normal and hard are pretty close.

OMG i played on easy mode bc i thought the loot pool stayed the same on each diff and its faster to kill the bosses anyway so i saw no point in changing it but now that i know this it will the my whole life fr fr (thx so much:face-red-heart-shape:)

Good video.

For future reference for your hands use  a docs website

For soul storms when I play on hard I get special 4/5 times and unique 1/5 times

I'm so pissed lol I play on easy and wondered why I was not getting unique or special gear turned it to normal and it comes flowing in lol nearly all unique or special gear now XD

ts doesn’t matter when you can literally just be invincible anyway

Wait, I never got asked for a difficulty?

I didn't even know there was a difference in loot. I just went with hard for the challenge

yoooo thats a impressive build one shoting the boss! May i have the gears that ur having plsss??

my friend keeps wanting to play on Easy because they think it’s boring to die a lot. like bro, get good 🙏 thank you for testing this

lowkey forgot easy mode was on for so long because my build just fried everything in other difficulty's and thought the game was broken

Wait... we can change difficulty? 0_0

bro you lowkey carried my game with your videos thanks bro keep uploading. The farm video was goated but why do you run banner instead of grind stone?

So wait so hard and normal? Are equal? Witch is better

how are you seeing  how much damage your weapon does?

am I a coward for switching to easy just to kill monarch for the storyline