A controled round feed bolt can, of course, feed a cartridge even if the gun is up-side-down.Most havea massive non rotating extractor that will pull the most stubbornly stuck cases from the chamber. The downside to them is that you can not drop a round into the chamber and close the bolt with out possible doing damage to the extractor they muct be fed from the magazine so that the rim of the cartridge can slide up under the extractor. These designs also use an ejector at the rear of the receiver insteaad of the plunger on the bolt face like a push feed bolt. This type of ejector is prefered by many becasue it will throw a spent case a long ways depending on how forcefully you work the bolt.

A push feed bolt can single feed cartridges because the exctactor moves and is able to "pop" over the rim of the cartridge. The downside is that they aren't as strong and can not pull some stuck cases from a chamber. The plunger tupe of ejector used on the push feed bolts applies pressure to one side of the cartridge head thus causing improper case to chamber alignment and has the same ammount of pressure regardless of how fast you work the bolt so it basically throws a case the same distance every time.

The controled round push feed is able to do both. The cartridge slides under the extractor when fed from the magazine and is held in place securly but it the shooter is also able to drop a round into the chamber becasue the bolt has a moveable extractor which pops over the case rim. This design also uses the fixed position ejector at the rear of the receiver.