Drivetrain setups that deliver power to all the wheels on a vehicle come in several shapes and under several names. Defining and telling them apart has always been a hot topic for car enthusiasts, so I've created this thread. Keep in mind: 1.) This thread is only about vehicles with four wheels (to simplify things ) 2.) This thread is for discussing powertrains. Stories and photos of your cars/trucks and offroading trips belong to other threads! My opinion: AWD can either be permanent or automatic on-demand. In case of the latter, the driver cannot switch between modes as the AWD mode is engaged automatically when wheels slip. Despite popular opinion, AWD cars can have a hi-lo transfercase. 4WD is always driver-operated on-demand. 4WD mode is only for offroad applications. Can be switched on and off either from inside or outside. 4X4 is a synonym for 4WD.