entry guards are plastic runners that run along the inner door sill so you dont scuff the paint. The standard ones come with a silver Z badge on but the extra ones have a silver plate with a Z badge on. Look a bit flashier.
Don't get from the dealer. You can get them from Holdcroft or MJP (As with any other OEM Nissan part including the Tonneau Cover). Both do forum discount which you'll need to contact a Admin/Mod for the discount code.