Order Phoenix

What is the difference between order of the phoenix and aurors?

In Harry Potter, there is The Order of the Phoenix but then there are aurors that work for the Ministry of Magic who make actual careers out of chasing Death Eaters. So what is the difference? One is just a group and the other is hired?

yes aurors are hired by the ministry and their job is to capture dark wizards.
the order of the phoenix is a group of people (aurors and non aurors) who got together (not hired by the ministry) to find out things about voldemort and his supporters, and their ultimate goal is to bring him down.
the difference is when voldemort takes over the ministry he also took over some of the aurors that work there, but the order of the phoenix stayed a solid group to destroy him.

Order of the Phoenix International Trailer