Double post. Sorry. Whatever
All types of drawn(motorized) vehicles have their axle configuration in this little NumberXNumber formula declared. Unfortunitly, this standard is, although globally used, not understood well enough and leads to a lot of different interpretations.
The first number is how many half axles the vehicle has and the second number says how many of those are under power(at all times, a truck may have all wheel drive but only when engaged, since the world doesn't make sense, a 4 half axle truck with engaging All wheel drive can be both 4x2 and 4x4, depending on who you ask)
Since many truck configurations are rare, you can usually educatedly guess, what configuration the truck has. In 80% of cases, a truck has it's rear axles driven. For example. 4x2, 6x4, 8x4
Dump trucks, Fire trucks and Expidition trucks often come with all wheel drive. 4x4, 6x6, 8x8 (even 10x10 if you're swiss and near a quarry).
Semis have only the tractor described, so you can only have 4x2, 4x4, 6x4 and 6x6. The trailer is never driven by the main motor.
The people who seem to have the most trouble with this are americans. First, they consider pickups like the Ford Rander or F150 to be a truck(to make their ego feel better) and you will find the configuration have the number of wheels on it. So if your truck has 2 axles but the rear has duallys, it all of a sudden becomes a 6 wheeler and you might see a "5ton 6x4" advertised which is complete nonsense because most trucks can run Singles and Duals like they want.
