der Transporter
van
A medium-sized motor vehicle used mainly for transporting goods or a small group of people; a small transport vehicle or delivery van.
Für den Umzug haben wir einen Transporter gemietet.
We rented a van for the move.

van / transporter
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van
A medium-sized motor vehicle used mainly for transporting goods or a small group of people; a small transport vehicle or delivery van.
Für den Umzug haben wir einen Transporter gemietet.
We rented a van for the move.

The word is derived from the verb 'transportieren' (to transport). The ending '-er' here denotes a thing that performs an action. A 'Transporter' is therefore literally something that transports.
Die Möbelpacker haben den Transporter schnell beladen.
The movers quickly loaded the van.
In connection with the vehicle, 'Transporter' is often used with the verbs 'mieten' (to rent), 'fahren' (to drive), 'beladen' (to load), or 'entladen' (to unload).
Wir müssen für den Umzug am Wochenende einen Transporter mieten.
We need to rent a van for the move this weekend.
You can recognize the science-fiction meaning from words in that field, such as 'Raumschiff' (spaceship), 'beamen' (to beam), 'Planet' (planet), or 'Crew' (crew). Without this context, it almost always means the vehicle.
Der Captain gab den Befehl, den Transporter zu benutzen.
The captain gave the order to use the transporter.
van
'der Van' and 'der Transporter' can both be larger vehicles that offer more space than a normal car. 'Van' often sounds more like a vehicle for people, for example for a family or a travel group. But it can also be used for smaller transports. 'Transporter' emphasizes the purpose more strongly: things, goods, or furniture are meant to be transported. The words can be confused because some vehicles look similar. When people are the main focus, 'Van' is more natural. When the cargo area and transporting things are important, 'Transporter' fits better.

Der Transporter steht morgen vor dem Haus, damit wir die Möbel einladen können.
The van will be in front of the house tomorrow so that we can load the furniture.
Herr Weber fährt mit einem Van in den Urlaub, weil seine ganze Familie mitkommt.
Mr. Weber is driving a van on vacation because his whole family is coming along.