I will caveat my answer by saying that my knowledge of RFDS charter is now 6 years old and things may well have changed since then. However, the charters done out of Alice Springs were clinic runs, that is, taking a doctor and nurse (usually) to a community to undertake clinics at that community.
I also used to do a monthly clinic run out of Tennant Creek to the Barkly cattle stations for the RFDS. I never heard of any patient transfer flights or evacuation flights associated with those charters. In fact, the aircraft that I flew was the only one equipped for such a flight as it was set up for patient transfers from the Tennant Creek hospital. I am not saying it wasn't done, just I never heard of any. The RFDS decided to use the Tennant Creek aircraft as they decided it was safer flying than the driving they had done previously.
I also did some charter flights out of Darwin. Different company and I am sure they weren't through RFDS but possibly for NT Health. Same thing though, a doctor going to a community to conduct a monthly clinic.
The clinic runs were charters, the patient transfers were airwork.