Kind of obvious but just to clarify:
Pro Crew: people paid to be on this ship. Other then the maritime crew the pro crew is made up of a cook, cook's mate, medical officer, and 3 program staff (who take care of trainees and volunteers).
Maritime Crew: the people paid to sail this ship. I've heard the maritime crew, if the had to, could sail/motor this ship on their own. Among the maritime crew there are different positions and ranks.
First off, the officers. There is always an officer "on watch" and they have navigational certificates as well as sailing experience. In order of rank the officers are the Captain, Chief Mate and First Officer.
Also on each watch we have an AB (able bodied seaman) on duty. The 4-8 watch has 2 ABs. Not sure why, my first sail there was only 1 but another AB joined so there are 2 now. The ABs are the lowest ranked of the maritime crew and do a lot of the physical work: cleaning, sail manoeuvres, maintenance, etc. as well as organising all the volunteers and trainees as far as work to be done while on watch is concerned.
Other then these positions we have a chief engineer (obvious what he's here for) and a bosun (kinda like an amazing maintenance man for a ship).
Our pro crew come from around the world! We have crew from South Africa, Australia, Denmark, Germany, Canada, the States and Norway.
Us in the lower ranks are divided between volunteers (have more experience, mostly those who have spent a year on the ship as part of Class Afloat, on board for longer periods of time) and trainees (those who are sailing for a week or two, what I was on my first sail). Generally speaking we do all the same jobs with the volunteers taking on slightly more responsibility and leadership.
An exception to all this is Halley. She was originally hired as program staff and still fulfils that duty, teaching us about knots, navigation, sails and all things seamanship; however she's also now part of the maritime crew as an Ordinary Seaman (under an AB). She switches back and forth filling in where needed and generally being useful. I highly suggest you read her blog post describing her role here. Click <a href="http://vagabondtreehugger.blogspot.com/2013/07/
so-what-is-it-you-do-again.html?m=>here to go!</a>