Actually, Paul's gospel differs from Jesus's gospel.
While Jesus preached the gospel from the moment he came out of the wilderness, and it had nothing to do with the cross, Paul states very clearly to preach not the gospel of Jesus, but to preach his own. in Romans 2 verse 16 we read: "In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.
And again, Paul tells Timothy, in 2 Timothy 2 verse 8: "Remember that Jesus Christ of the seed of David was raised from the dead according to my gospel."
The problem is that Jesus told the Apostles to go an preach the gospel to all nations. The gospel Jesus is referring to is not the gospel of Paul, but is the one he started preaching when he came out of the wilderness.
Paul preached a gospel based upon the resurrection, while Jesus preached one based on forgiveness: through turning from sin, to his teachings of mercy and forgiveness, love to all (especially your enemies) and detachment of and from materialism, but make no mistake this is not Paul's gospel, for Paul hardly utters Jesus's words at all.
8 And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, "In you shall all the nations be blessed."
9 So then, those who are of faith are blessed along with Abraham, the man of faith. - Galatians 3:8-9
There is one gospel congruent through all the ages. The OT saints looked forward to the coming Christ, the prophet promised by Moses:
17 And the LORD said to me, 'They are right in what they have spoken.
18 I will raise up for them a prophet like you from among their brothers. And I will put my words in his mouth, and he shall speak to them all that I command him.
19 And whoever will not listen to my words that he shall speak in my name, I myself will require it of him. - Deuteronomy 18:17-19
while the NT saints look back to Christ crucified. Jesus preached the Kingdom of God, of which He is King. Once resurrected the mission Jesus proclaimed changed, but the gospel itself remained the same. It is in and through faith we are justified, both Jew and Gentile.
Jesus is Paul's Lord, and all Scripture is God breathed. One, and only one gospel was given by God to be proclaimed by man amongst the nations. Christ is not divided.
18 And Jesus came and said to them, "All authority in heaven and on earth has been given to me.
19 Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,
20 teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age." - Matthew 28:18-20
Note: This is the resurrected Christ speaking. So what is it that Jesus is speaking about concerning "all I have commanded you"? We know this:
He presented himself alive to them after his suffering by many proofs, appearing to them during forty days and speaking about the kingdom of God. - Acts 1:3
And by Paul's account we know:
Paul, an apostle-not from men nor through man, but through Jesus Christ and God the Father, who raised him from the dead- - Galatians 1:1
11 For I would have you know, brothers, that the gospel that was preached by me is not man's gospel.
12 For I did not receive it from any man, nor was I taught it, but I received it through a revelation of Jesus Christ. - Galatians 1:11-12
So then these commands Jesus describes must align with Paul's apostolic mission.
And speaking to the commandments John explains:
23 And this is his commandment, that we believe in the name of his Son Jesus Christ and love one another, just as he has commanded us.
24 Whoever keeps his commandments abides in God, and God in him. And by this we know that he abides in us, by the Spirit whom he has given us. - 1 John 3:23-24
This then also agrees with Paul's gospel of faith working through love:
For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love. - Galatians 5:6
The gospel is not divided. You are confused.