Horrible ending on this thread: Both of these games use deferred rendering. The difference between the two is that UE5 games renders hair with dithering inside the deferred textures: youtu.be
Cryengine forward renders non-dithered hair on top of the completely lit deferred rendering: youtu.be
Then hair is forward rendered on top of the deferred lit scene: youtu.be
youtu.be
It's 60 microseconds more (basically nothing) to render CryEngine's way. And apparently some hair is rendered first in the deffered stage according to the dude in the video.
UE5 has the ability to forward render objects after the deferred lighting too. Devs are just too lazy/incompetent to do it that way in unreal.