How does all wheel drive differ from two wheel drive and 4 wheel drive?

the main difference between 4 wheel drive, and awd is the presence of a low range. an awd will not have a low range.low range is for maximum power when pulling.a awd vehicle will not be used by any sensible person for heavy pulling,so therefore does not need a low range. also a 2 wheel drive, will only send power to one axle. whether both tires receive power depends on if the differential is an open,limited slip, or locker equipped. an open diff will send power to one side only. limited slip will only allow a small amount of slack before the tires turn together,and a locker will tie them together all the time,except in a turn. an awd system uses a clutch inside the transfer case to allow the slippage for a turn,so it will not have to disengage from powering both axles.

Two wheel drive means only two of your wheels are getting power from the engine. Four wheel drive is an optional way to make all four wheels get power from the engine when you need it.

All wheel drive is basically the same as four wheel drive only you cannot shut it off therefore all four wheels get power from the engine all the time.

well two wheel drive should be self explanitory as well as all wheel drive which is similar to 4 wheel drive but different in the way that 4wd is more sharing/independent with the power:) if one wheel loses traction more effort will be put to make that wheel gain it back

most cars that are all wheel have sensor that lets it know when it needs 4 wheel drive and it automaticaly goes to 4x4