I'm military so I can't answer that question. I don't believe its a separate approach endorsement (admitting that I don't know the new licencing system very well).
Let me ask you a question with a hypothetical - say your CJ-3 is certified and equipped with a CAT III ILS with autoland and your Caravan is only Cat I ILS. Do you think its reasonable that you might have to use different procedures, different automation, and have a deeper level of understanding to fly CAT III to AL than to fly a CAT I. It's the 'same' approach after all.
This is no different, but to a narrower scope of difference in my opinion.