Special oil filters for AFN engines? - especially @Michael II

Hi.

I've noticed that the AFN engine (in the 1997 Golf 3) is supposed to use a different oil filter than the 66kW engine (1Z, AHU).
Question: Why? Are only the filter characteristics (pore size, etc.) different, or also the mounting dimensions (thread size, etc.)?

If both filters are compatible with the AFN engine: What problems would one encounter with a 1Z / AHU filter?

Hello Ulf,

In my opinion, the flange on the oil cooler has a different...
Sizes or variations (for example, in the 1Z model, there is a mother between the radiator and the filter). Whether the pore size or the filter element has changed is something I am not aware of.

...so there is hope that a "wrong" filter would be detected during the installation attempt.