What was the smaller semi???

[George S. Bower]

View attachment 264504

How does this work?

Possibly one pair of contacts for each one the 4 large battery modules. Other space for control and safety ground circuits.

good possible explanation here:

Close-up look at the Tesla Semi "Megacharger" charging port

 

[Farmertom]

Both trucks are the same, the white one is just taller.

The top of the cab is still the "roof" as stated and although some extend to the full height of the white truck (referred to sometimes as penthouse suites), most are built like the dark truck with fairings or extensions installed to increase the height for taller trailers. If you look up between the truck and trailer over in that space you'll sometimes see items like bicycles, tarps and such stuffed in there.

European trucks haul basically the same loads as we do in North America (remember they haul intermodal freight containers just like virtually everywhere else worldwide Intermodal freight transport - Wikipedia ) but they must be lower, shorter and way more maneuverable hence the tendency to run single axle trucks with triaxle trailers. You can see the differences here

. Trucks with tag trailers as shown above are also common but of course then you're dealing with two smaller containers instead of one big one, I'd say this style of truck is way more common for hauling divisible freight like lumber and such, that truck in the picture the sides are actually curtains that slide open so forklifts can access the cargo. Here we haul freight like that on flatdeck trailers.