We’re looking at the item level of loot from Amirdrassil on all four difficulties.
As is tradition with Dragonflight raids, the bosses drop progressively better loot.
On Raid Finder Difficulty the item levels are 441 > 444 > 447 > 450 (last two bosses).
Mythic Difficulty starts at Item Level 480 (1/4 Myth Track) and the final two bosses drop gear upgraded to 4/4 (Item Level 489).
Difficulty
Item Level
Raid Finder
441-450
Normal
454-463
Heroic
467-476
Mythic
480-489
