What is the difference between the prophet of the Old Testament and the prophet of the new Testament?
An excellent resource providing Old Testament and New Testament scriptures regarding the prophets is found at Church Restoration.org.
The Old Testament prophets were fore-tellers given the word of God by God- in other words, a spokesperson for God. Simply put a prophet is “one who speaks for God”.
“Hear now My words: If there is a prophet among you, I, the LORD, make Myself known to him in a vision; I speak to him in a dream. Not so with My servant Moses; He is faithful in all My house…” (Numbers 12:6-7)
In the Old Testament, prophets were told by God of events that that He had declared to occur in the future and foretold the prophet. Prophets were the mouth of God for the communication of his mind and will to men:
“I will raise them up a Prophet from among their brethren, like unto thee, and will put my words in his mouth; and he shall speak unto them all that I shall command him. And it shall come to pass, that whosoever will not hearken unto my words which he shall speak in my name, I will require it of him…” (Deut. 18:18)
With the exception of Jesus and Jesus’ beloved disciple John to whom Jesus gave the book of Revelation, the New Testament prophets mostly provided practical, situation-specific messages from God. In the New Testament, the role of the Prophet is to speak for God and to exhort and direct the body of Christ.
“And God hath set some in the church, first apostles, secondarily prophets, thirdly teachers, after that miracles, then gifts of healings, helps, governments, diversities of tongues….And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers…” (1 Cor. 12:28; Eph. 4:11)
Prophet and the gift of prophecy is not exclusive to men:
And Deborah, a prophetess, the wife of Lapidoth, she judged Israel at that time. (Judges 4:4)
And the next day we that were of Paul’s company departed, and came unto Caesarea: and we entered into the house of Philip the evangelist, which was one of the seven; and abode with him. And the same man had four daughters, virgins, which did prophesy. And as we tarried there many days, there came down from Judaea a certain prophet, named Agabus…” (Acts 21:8-10)
In the New Testament church the role of the prophet is one of aiding the various members in hearing from God and placing them in the correct path of God’s will. There are some New Testament prophets that use their gifts to predict the course of various members of Christ’s body as well as predicting the course of some individuals.
And as we stayed many days, a certain prophet named Agabus came down from Judea. When he had come to us, he took Paul’s belt, bound his own hands and feet, and said, “Thus says the Holy Spirit, ‘So shall the Jews at Jerusalem bind the man who owns this belt, and deliver him into the hands of the Gentiles.'” Now when we heard these things, both we and those from that place pleaded with him not to go up to Jerusalem. (Acts 21:10-12)
Prophets operate primarily in the revelation gifts. They are maintainers of order in themselves and Body at large.
Another resource expounding deeper into New Testament prophets is found at Desiring God.