Is black PVD a better or harder finish than black oxide for watch cases and bracelets?

I am having an Orfina Porsche Design watch refurbished by Orfina at present and I believe they re-colour with black oxide (yet to have this confirmed).

I now that some of the Orfina PD watches where done in both black oxide and PVD.

Does anyone have any input or thoughts as to the different qualities of finish between the two.

Thanks