Couple of things:
1 - Enslaved is multi-platform developed on Unreal 3 Engine
2 - Heavenly Sword was developed on custom engine (I believe) built specifically to PS3 architecture
3 - Enslaved is based around full 3D freedom of movement
4 - Heavenly Sword is more like a God of War title where the camera is not fully 3D at the view is theirfore more controllable by the developers
In short, you're talking a custom engine developed on one platform vs a developer getting to grips with a middleware engine that is both multi-platform and rarely looks as good as it could when used by anyone other than Epic - the engine's developers.
No big surprise. I'd note they're using the same engine for DMC - that should be interesting, as I personally think the U3 engine may not best suit the traditional fast paced - and camera locked - DMC gameplay style. I'll be curious to see how it goes, but I'm expecting it to be slower for sure.