@federico.domeniconi thank you for the question. The discrepancy is due to the coordinate system in Isaac defaulting to Z-up. Because cameras in USD are always y-up regardless of coordinate system, an additional rotation is added with Replicator to provide intuitive camera orientation that is consistent with the rest of Kit - the same rotation is added when creating a camera using the menu system (Create->Camera). You can cancel out the additional rotation in a Z-up stage by creating a camera as so:
import omni.replicator.core as rep
camera = rep.create.camera(position=(0.0, 0.0, 1.0), rotation=(-90, -90, 0))