I think the poster means Halo-style (with a physical can up there) vs. Lightolier (the trim is held up by a friction ring). This only matter if you plan to replace the fixture.
As for bulbs, I'm sticking with halogen in the bathroom (we have the same setup: two BR40s over our sinks). The LEDs I tried (e.g. Sylvania, Ecosmart) have a throw that is too wide (120°), which is great for lighting up the rest of the bathroom, but doesn't deliver enough light straight downward over the sink. Also, they are weak in the deep-red part of the spectrum and make skin and makeup look a little off.
For now I'm sticking with 70-watt halogens from Philips and Sylvania. These are newer designs that use infrared reflection to save energy. They put out around 1300 lumens and have fantastic color rendition. Unlike our kitchen, the lights in the bathroom are used for only a short period of time, so switching to LEDs won't save us much on our electric bill.
