Differences between getting serviced by an RSV and an AD

[Snakeyes]

What's up guys?

I'm just purchased a used 99' air-king w/ blue arabic dial. It's going to be my first Rolex and I'm stoked!! The guy that I purchased it from is the original owner and he's told me that he's never gotten the watch serviced and that the caseback has never been opened.

Anyway the first thing I'm going to do is take it in for servicing and an appraisal. I was wodering if I should take it to an RSV or an AD to get the servicing done?

Also is there really big differences between the two and if so what they're?
What gets done to your Rolex when it gets serviced? e.g.- oiling, cleaning of dial etc.

Any opinions or past experiences will be appreciated.

Thanks!!