Body bars and barbells could be used interchangeably, IMO. There are advantages to each (barbells are adjustible, body bars are more balanced), but they are similar.
As for barbells vs dumbbells, I personally prefer dumbbells to barbells on upper body work (to make sure that the strong side isn't compensating for the weak side, and to work the stabilizing muscles) and barbells for squats (because it's easier to hold a heavier weight in the barbell position), but I vary between the two.
I notice your post says "barbellS" in the plural. Do you think you need more than one? You don't (unless you want one). A barbell with it's plates really wouldn't take up much more space than the body bars. Troy Lite barbells are pretty compact, and the plates are rubber coated so they won't rust. When you are done working out, you can put the plates and the bar (with not plates on) under the sofa or bed. I have a small plate rack that holds all my barbell plates (I actually do have 2 Troy Lite barbells, because there are some workouts where I like to keep two weights ready and not change, like "Ripped" by Jari Love).