What is the difference between the neutral and parking gear?

Answer 1

that's the dumbest car question i ever heard im a mechanic so in neutral u can move around and stuff in park u don't move

When neutral is selected the output and input shafts are disengaged from one another and from the transmission casing. The car can roll and the engine can rev freely. Selecting the parking gear engages a solenoid connected to a spring loaded dowel pin which lines up with one of many holes on the gear set it is next to.

So when you put your car in park on a steep hill and let go of the brakes, it begins to move, but can not do so more than a tiny bit before the spring loaded pin engages the gear set and locks the output shaft. Engine can rev, but you can't roll anywhere. Hence the name 'Park'.