There are a lot of different CAD packages which don’t normally work together. However, the actual modeling is basically the same. Putting a hole in something is putting a hole in something no matter what the database looks like.
So apparently it’s possible to describe (nearly) all of the operations that CAD modeling programs use to do the modeling in a neutral language. Stick an appropriate plugin onto your favorite CAD modeling program and it will translate your actions into the neutral language, send a message to everyone else, and a plugin on their favorite CAD modeling program(s) will execute the same operation in real-time.
As long as you’re okay taking turns you can all work on the same model, from different places, using different programs.