They are basically the same. Rear facing sounds better than backwards facing, because backwards suggests something wrong for example "he put his shirt on backwards" ie incorrectly. Rear facing means facing to the rear of an aircraft or vehicle.

(1) They have the same meaning, but in my opinion "rear-facing" is more commonly used than "backward-facing" when people talk about car seats. (2) The first thing I think of when I hear "rear-facing" is a baby's rear-facing seat in a car. You can use either term for any car that has seats that are backwards. There can also be backward-facing seats in airplanes, which apparently is more safe than front facing seats in the event of a plane crash. http://aviation.stackexchange.com/questions/11476/why-are-passenger-seats-not-facing-backward-on-an-airplane