The difference between zinc plated fasteners and hot dip galvanised fasteners is actually quite significant. Zinc is usually around the 20micron thickness possibly less, whilst galvanised is usually >60micron usually quite a bit more.

The process for applying the coatings as well as the end use of fasteners with the two coatings is also quite different.

> The difference between zinc plated fasteners and hot dip galvanised fasteners is actually quite significant

Yeah, but those aren't listed under coatings. They're listed under materials. And they certainly don't list the same variety of zinc coatings you could find at McMaster-Carr.