no, i don't think there is much difference in "weight" between unity, ogre and gamestudio. i guess you mean scene management? the basic scene management they use probably is quite similar. some hierarchical data structure (octree, abt,...) with front to back sorting for drawing or something like that.



ogre has the advantage that you can extend it with your own more specialized scene managers if you have the skills.

and gamestudio still has the old quake style bsp scene manager around which may have advantages for indoor scenes but is limiting in the kind of geometry you can use and results in annoying workflow.