Hopefully I will get this right.

Controlled Round feeding is when the bolt captures the next round in the magazine and pushes it into the chamber. The round has to move up into the face of the bolt. You cannot single feed this system without pushing the round down into the magazine well and cycling the bolt.

Push Feed sytems do just that. They push the next round into the chamber without really guiding it. The bolt face does not hold the case at all. You can drop a round in and just push the bolt home with this system.

Winchester's CRPF system used the best of both systems. You can single feed the rifle or pull one from the magazine. The front of the bolt captures the next round in a linear motion and then guides it into the chamber. I have this system in my Winchester Super Shadow and it works very well.