All crew members need to know how to fight fire, control flooding and stand watch. After that, there are dozens of seagoing ratings or job specialties in the US Navy.
See the link.
Pretty much the same as with any society. Cook, policeman, engineer, doctor etc.
Sailor
Captain
Captain
Seafarer
Eurylochus
40
A sailor is any member of a ship's crew.
Popularly, an on-ship cruise line employee is known as a "crew member," but may either be crew, staff, or officer.
There is one crew member for every two passengers. Our boat had 2000 passengers and 955 crew.
Minion
The members of the ships crew that attended to the needs of the passengers were the stewards and stewardesses.
Commanding the ship's crew, taking care of navigating and keeping the ship's log book.