GPS and VOR are different!
? VOR’s have a CDI/OBS that “resolves” your relation to a particular course.
? GPS’s normally provide CDI information independent of the OBS setting (like a localizer!). They may also have an OBS mode.
To avoid confusion, set your OBS to the desired track anyway!
? VOR’s reference courses to published “VOR North” (approximately Magnetic).
? GPS’s use models of the earth’s magnetic variation, which may cause small differences on charted courses.
Not an issue in fix-to-fix navigation.