Here is what B+W says:
B+W Standard Filter Mount F-Pro
Compared to the earlier B+W standard filter mount, the B+W Standard Filter Mount F-Pro has been improved considerably.
While maintaining the excellent quality of materials, fabrication, and high mechanical stability, the new F-Pro mount has become thinner, so that now it can also be used on many wide-angle lenses without the danger of vignetting.
While thinner than the old F-Pro mount, it is still thicker than the B+W "Slim Line" filters and still has front filter threads.
B+W SLIM Wide-Angle Filters
B+W has introduced the thin
-ner line of B+W “SLIM” wide-angle filters without a front thread that are a mere 3 mm thick, designed for super wide-angle lenses that are prone to vi
These are the ones you should probably stay away from if you don't like your Tiffen "thin" filters.