There is no difference between a work file and a physical file, a work file is simply a physical file that is used to store temporary data in. It’s like, for example, the difference between a taxi and a car.
When I use a “work file” I tend to copy an empty file from my data library to QTEMP and then use overrides to point to the copy in QTEMP. That way, when the job ends QTEMP is cleared and I don’t have to worry about the disk space used by any work files.
Hopefully this should make it clearer, if not let us know.
All the best