Priest, Minister, and Pastor are job names. Priest is a Catholic ordained minister. Pastor is a specific title within a church for a job performed by a minister. Minister is more generic. The most generic is one you didn't ask about, Clergyman. Reverend is an adjective used to describe someone who holds one of those jobs. There is no such thing as a "Reverend" because it is not a noun. Look up the word "Revered" and you will find the better definition for Reverend. We talk of the Reverend Billy Graham, but he is not a Reverend. He is a Minister. The Reverend Martin Luther King was a Minister. The Reverend Al Sharpton is a Minister. Sort of like a term of respect. You call the Pope His Holiness Gregory (whatever number), but he isn't a "Holiness" - because that is a quality, not a thing.
People may call themselves all sorts of names with titles but what really matters is what God says. The bible is the inspired word of God and a manual on how to live our lives. (2Timothy 3:16 All Scripture is inspired by God and is useful for teaching the truth, rebuking error, correcting faults, and giving instruction for right living, 2Timothy 3:17 so that the person who serves God may be fully qualified and equipped to do every kind of good deed.) Christ said that we should live by every word of God. (Luke 4:4 And Jesus answered him, saying, It is written that "man shall not live by bread alone, but by every Word of God.) Notice the last part of this verse... by every word of God. So now that it is settled let's see what God says about his chosen ministers. (Titus 1:5 I left you in Crete, so that you could put in order the things that still needed doing and appoint church elders in every town. Remember my instructions: Titus 1:6 an elder must be without fault; he must have only ...