The relevant passages are:
And they put up over His head the accusation written against Him: THIS IS JESUS THE KING OF THE JEWS.
And the inscription of His accusation was written above: THE KING OF THE JEWS.
And an inscription also was written over Him in letters of Greek, Latin, and Hebrew: THIS IS THE KING OF THE JEWS.
Now Pilate wrote a title and put it on the cross. And the writing was: JESUS OF NAZARETH, THE KING OF THE JEWS.
There is no reason to suppose that all four of these verses can’t be true concerning the inscriptions on the cross. John (John 19:20) tells us that the charge against Jesus was written in three different languages: Greek, Latin, and Hebrew. Since Matthew’s audience was mainly Jewish he likely quoted the Hebrew inscription (the common language of Palestine): “THIS IS JESUS THE KING OF THE JEWS.” Since Luke’s audience was mainly the Gentiles he likely quoted the Greek inscription-“THIS IS THE KING OF THE JEWS.”
John mentions that Pilate wrote an inscription (likely someone wrote it for him), and since Latin was the official language of the Romans, John likely quoted the Latin inscription:“JESUS OF NAZARETH, THE KING OF THE JEWS.” Mark could have quoted any of the inscriptions, but merely abbreviated his version to the most relevant portion of the inscription: “THE KING OF THE JEWS.”
Although all four inscriptions are slightly different in English, they all contain the statement, “THE KING OF THE JEWS.” This was the charge brought by the Jewish leaders against Jesus in the Roman trials (Luke 23:2), and by itself is sufficient to describe Jesus’s “crime.”
Thus, the content of the four inscriptions is identical, and the minor differences can be attributed to the language of the inscription being quoted by the author or the author’s liberty to quote the part of the sign that he thought was sufficient in his historical account of the events.