A van has LPG from the factory when the vehicle is designed and built for LPG by the manufacturer, with injectors, tanks and engine controllers provided by the manufacturer.
A van is said to have been converted to LPG before sale when it is designed and built as a gasoline van, and is converted to be able to consume LPG by the manufacturer or an associated company. In this case, all the elements of the LPG equipment are guaranteed by the manufacturer
It is called a conversion to LPG after purchase, when the user has bought a gasoline van and, once in his possession, installs the necessary equipment to be able to consume LPG in a workshop authorized by an LPG equipment manufacturer . In this case, it is the manufacturer of the LPG equipment that guarantees the conversion
Buying a van that runs on LPG is a good idea both in terms of savings and ease of use, as you can always continue to use petrol in case of need.