The passenger seat description, is relative to it's use in Westfields, where in many classes a "seat" of some description is required. It's the low back/lack of head rest. - Helps make it lighter weight, and reduces the drag of having a full size seat sticking up.
They're comfy seats though, in their own right.
Used as a drivers seat though, the lack of headrest can be problematic to say the least. For competition purposes, you'd normally have to install a separate, mandatory headrest, to overcome this. On a car that's already through IVA, I don't off the top of my head recall it still being mandatory, BUT, total lack of a head rest/support could see a very minor shunt turn into something catastrophic for your head/neck. (We each have our own acceptable risk levels etc). Much better to add one.
This type of seat is the Westfield Sports Seat. (Not Sport Turbo, just Sports)