From what I understand, once a bromine pool, always a bromine pool. If you start with bromine and later decide to switch to chlorine, you will need to drain the pool and flush the plumbing to get rid of all the bromine. A bromine feeder works off the same principal as a chlorine feeder. You load it with pucks and replenish them as they dissolve.
With a SWG you add salt to the pool and add additional salt as needed to keep it at the level required to produce chlorine.
Both systems are less "hands on" than dosing with liquid chlorine or putting pucks in a floater. Both systems require the pump run long enough to deliver the chlorine or bromine at the levels needed to maintain proper sanitation. Both systems require frequent testing to maintain water balance.
You can do a google search for bromine at the bottom left of this page for more information.