If you look at the story about the greatest commandment in Matthew, Mark, and Luke you will see how the details differ but the basic message is the same.
In Mark 12:28-34 a scribe asks Jesus, "'Which commandment is the first of all?'" and Jesus answers, "'.....love the Lord your God.....'" and then adds, "'.....love your neighbor.....'". The scribe then says that Jesus is right and reiterates the two sayings from Leviticus and Deuteronomy. Then Jesus says to him, "'You are not far from the kingdom of God.'" (NRSV)
In Matthew 22:34-40 a Pharisee asks Jesus which commandment is the greatest. Jesus replies, "'.....love the Lord your God.....'" and adds that the second is like it, "'.....love your neighbor.' On these two commandments hang all the law and the prophets." (NRSV)
In Luke 10:25-28 a lawyer asks Jesus, "'what must I do to inherit eternal life?'" Jesus asks him what is written in the law. The lawyer answers, "'.....love the Lord your God.....and your neighbor as yourself.'" Jesus says he is right and , "'do this and you will live.'"
It can clearly be seen that the identity of the questioner differs, who asks who differs, the endings differ, but the message is the same in all three versions: "You shall love the Lord your God with all your heart, and with all your soul, and with all your might." Deuteronomy 6:5 and "you shall love your neighbor as yourself" Leviticus 19:18 (NRSV)
This should teach us not to get too hung up on the details of the narratives and parables but to look for the inner meaning.
(Scripture quotations (marked NRSV) are taken from the New Revised Standard Version Bible, copyright 1989 by the Division of Christian Education of the National Council of the Churches of Christ in the U.S.A., and are used by permission. All rights reserved.)