Pickup trucks, like other vehicles can come in a variety of different configurations depending on which is suitable for your needs. The main variation for pickups is in the cabin, also called a cab, which in turn affects the size of the bed. Here are the 3 main variations present in the market!
Single cab
Also known as a regular cab, this is the smallest variant offered in terms of cabin size, being only a 2-seater with 2 doors, but because of its smaller cabin size, the truck bed is also the biggest of them all, suitable for people whose job is to haul things around and commonly used as commercial pickups. This is also the cheapest variant amongst them all.
Extended cab
For the people who want something larger than a single but not as large as a double cab, the extended cab is the one meant for you. Mostly available as a 2+2 configuration with either 2 or 4 doors, there is extra space behind the front seats that has a small row of seats to carry passengers during short trips or to be used as extra storage inside your pickup.
Double cab
Also known as a crew cab and the most commonly seen on the road, this is the perfect variant for people who want a vehicle that can do it all, as it comes with 4 doors and full size second row seats that can seat families comfortably, yet still has the capability to haul stuff when you need it to, with the only sacrifice being a smaller bed to compensate for the increase in cabin size.
*Do note that cabin standards may vary between manufacturers, and for some models a short bed or a long bed option may be present, and the above is assuming the pickup to be the same length across all variations.