Good let's also compare.
Matthew 24:14
14 And this gospel of the kingdom will be preached in the whole world as a testimony to all nations, and then the end will come.
End times is a future event. Whole world is a unbound universal gospel that is fit for the whole world. Obviously the world grows and so does populations. Nations spread out. But the Gospel continues to fulfill the promise that it is reaching in every generation the known world.
But that is theology with different theological opinions. Back to the same Gospel not 2.
Romans 14:17
17 For the kingdom of God is not a matter of eating and drinking, but of righteousness, peace and joy in the Holy Spirit,
1 Corinthians 4:20
20 For the kingdom of God is not a matter of talk but of power.
Acts 19:8
Paul entered the synagogue and spoke boldly there for three months, arguing persuasively about the kingdom of God.”
Acts 28:23
23 They arranged to meet Paul on a certain day, and came in even larger numbers to the place where he was staying. He witnessed to them from morning till evening, explaining about the kingdom of God, and from the Law of Moses and from the Prophets he tried to persuade them about Jesus.
Same Gospel.
Hebrews 12:28-29 New International Version (NIV)
28 Therefore, since we are receiving a kingdom that cannot be shaken, let us be thankful, and so worship God acceptably with reverence and awe, 29 for our “God is a consuming fire.”
No other Gospel but Jesus Christ as admitted by Paul.
Galatians 1:6-7 New International Version (NIV)
No Other Gospel
6 I am astonished that you are so quickly deserting the one who called you to live in the grace of Christ and are turning to a different gospel— 7 which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ.
Christ brought in the New Testament. The good news had arrived. John 3:16 Christ died for all. Whoever would believe shall be saved. Not very legalistic sounding?
John 6:28–29
28 Then they asked him, “What must we do to do the works God requires?”
29 Jesus answered, “The work of God is this: to believe in the one he has sent.”
John must of missed the legalistic part. Again same Gospel.