Definitely 2 different topics:
With Crewed charters, the crew is taking care of the boat before and after the trip as well as provisioning. Also expectations for service (beds made, cleaning, meals, as well as planning the destinations and activity suggestions. The more experienced crews generally move to larger (and more expensive) yachts, for both a better "housing", as they live there even when boat not out on charter, and a "promotion" as the larger boats charter for more an therefore have higher potential for gratuity.

With bareboat plus skipper added, then this is basically a "boat driver". He or she has no other chores. There is a contractural fee the charter company adds for this service. The bareboat skipper "add on" fee is usually unrelated to the boat size/ pricing.

When unsure, I would recommend questions as you are considering booking a trip, and also hopefully FAQs of charter company covers this topic.(The hired skipper should know what the charter company FAQs regarding skipper and gratuity as well as provisioning for skipper)