The Messiah is a descendant through the male line of King David son of Jesse from the Tribe of Judah.
On the other hand, a Priest is a Cohen descended through the male line from Aharon from the Tribe of Levi.
The Messiah therefore cannot be a Priest because he is not descended from Aharon on the side of his father.
The Messiah is a Prophet as described in the Prophets, see Isaiah chapter 11 and other sources. See the Wikipedia section on Scriptural requirements for the Messiah:
Scriptural requirements
https://en.wikipedia.org/wiki/Me...
The Messiah will be revealed over a period of time. Differing prophecies may refer to different stages in the Messianic Process.
