Simplify the following text for a Grade 8 native English-speaking person.
Original: For vehicles with more than four wheels , AWD means all wheels drive the vehicle , to varying degrees of engagement , while 4WD means only four of the wheels drive the vehicle continuously .
Simplified: A Four-wheel drive ( also called 4WD , 4x4 ( `` four by four '' ) , all-wheel drive , or AWD ) is a vehicle on which all four wheels get power from the engine to move forward .