6×4
Videos
A 6×4 or six-by-four is a vehicle with three axles, with a drivetrain delivering power to wheels at the ends of two of them. It is a form of four-wheel drive but not one of all-wheel drive.
Typical American 6×4 tractor unit
1937 military lorry off-road
TACR2 airfield fire engine
Four-wheel drive
Videos
A four-wheel drive, also called 4×4 or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges.
The Jeep Wrangler (pictured is a TJ Wrangler) is a 4WD vehicle with a transfer case to select low-range or high-range four-wheel drive.
Center transfer case sending power from the transmission to the rear axle (right) and front axle (left)
The Lamborghini Murciélago is an AWD that powers the front via a viscous coupling unit if the rear slips
The HMMWV is a 4WD/AWD that powers all wheels evenly (continuously) via a manually lockable center differential, with Torsen differentials for both front and rear