What the vendor driver does that the generic one does not, and how to check which one is installed. Most of these pages exist because a job failed on one machine and worked on another.
How the driver pages are written
A page here is about the difference between what a device can do and what a generic driver reaches. Print and scan are the two things any generic driver covers; the scanner path, the duplex path, the tray selection and the manufacturer’s own options are usually where the difference starts.
Pages are written for a model rather than for a driver package, because the package changes and the model does not. Where a model has been tested against the library, the entry says so; where it has not, the page describes what the library expects and no more.