WOFT,
Not to worry, my gut feeling is that your english is MUCH, MUCH better than most of the rest of we forumites speaking your language. Thank you for participating on the forums, every now and then you come up with a term that has stumped me, thankfully, by the time I read it, another person has already asked about it, like today. I had no idea of what a "bakkie" might be, but guessed after reading your post that it related to a vehicle, was unsure if it meant a motorized scooter or what though.
The following is a very quick synopsis on trucks/vans/rigs. I suspect that other readers may have other descriptions and terms to share.
In the US, trucks come in several types that can be basically summed up in these very generic categories:
"Small" pickup trucks (like Mazda, Chevy S-10, Ford Ranger)
"Mid Size" trucks (like Ford F-150, F250)
"Full Size" trucks (like Ford F-350 & F-450) generally these will have 6 wheels which include dual rear wheels (2 on the back left and 2 on the back right, although I've seen some with only 4 wheels per vehicle.
Vans are basically boxes (with smoothed or rounded corners / edges) almost always have 4 wheels. I've seen (rarely) some that had tandem wheels on the rear (two wheels on the back left and back right, but instead of being side by side like on the big pick up trucks, they were one in front of the other.
These may be passenger vans with seating for 6 to maybe 12 or 14 people. Generally passenger vans have windows all the way around the vehicle. Typically these are used as mini school buses, taxis etc. Often seen at airports.
Cargo vans generally only have windows in the front, and on the driver and passenger doors, sometimes the two back doors may have them as well. These are very commonly used in construction / business / delivery work.
Then we get into what I think you called "Lorries"... my guess is that this would cover Grumman step vans and the like. (Big aluminum box bodies, one or two seats in the front, four or six wheels, tall enough to stand up in.) Commonly used for parcel delivery and some construction work.
Then there are the Tractor Trailers (slang names include: "Semi" or "Semis" as a contraction of "Semi Tractor Trailer" , and "Big Rigs")
These are your large commmercial carrier trucks, typically with 6 to 10 wheels on the tractor or "Cab" of the truck, and 8 or more wheels on the trailer portion. Do a websearch using the following manufacturers for photos. Peterbilt, Kenworth, Mac, White, GMC. There are others, these were the ones that quickly spring to mind.
Hope this helps.
Regards,
Comanche7