Trying to get into it, and I'd rather do it on Requiem. Is there any differences in question of the routes or glitches ?

Yes, there are, and quite a few. I suggest you read this post for more info: https://www.speedrun.com/sotn/guide/4yliu
You should also watch one or two Any% NSC runs side to side to get a feel of how different the versions are and how different skips are performed. For instance, Death skip is performed by backdashing out of the room where he steals your stuff instead of using the neutron bomb; there is no shop glitch, which means no dupe and infinite mana prisms; and the relic skip at the end of the room is different too as you don't need a heart refresh to cause the camera to shift you one screen length.