God uses DISTINCTIVE terms to designate the various items of good news, gospels. There is "the gospel of the kingdom" (Matt. 9:35), "the gospel of the grace of God" (Acts 20:24), "the gospel of the circumcision" (Gal. 2:7), the "gospel of the uncircumcision" (Gal. 2:7).
SURELY if GOD distinguishes between these gospels (good news) they CANNOT BE EXACTLY THE SAME.
God has revealed His good news (gospels) to man progressively. From Adam and Eve to Abraham to Moses to David to the prophets to John the Baptist to Matt Mark Luke John. The gospel He shared with Adam and Eve was that the woman's seed should some day crush the head of the Serpent (Gen. 3:15).
The good news (gospel) that He preached to Abraham that in him (Abraham) all nations should be blessed.(Gal. 3:8).
On and on through OT Scriptures God proclaims more and more good news to man.
And it does not change with the NT. The Lord sent His apostles to proclaim "the gospel (good news) of the kingdom" (Luke 9:1-6). But note: At the time they were given this, they did NOT EVEN KNOW that Christ was to die. (Luke 18:31-34.
The gospel of the kingdom is the good news that the Kingdom, once prophesied, was at hand. This gospel takes us back to David, with whom the covenant of the kingdom was made. This is preached by the 12 during Christ's time on earth and after His crucifixion and until Israel is blinded (temporarily) and set aside (Acts. 28). And it will be preached again during the tribulation and the return of Jesus Christ to set up His millennial Kingdom.
What is the good news (gospel) of the circumcision? This gospel (good news) takes us back BEFORE David to Abraham, with whom the covenant of circumcision was made. (Gen. 17:11)
The gospel of the uncircumcision takes us back BEFORE David and Abraham to ABRAM who, as an UNCIRCUMCISED HEATHEN, was JUSTIFIED BY FAITH.
The gospel of the grace of God is based solely on grace, no difference between Jew and Gentile, no relation to ordinances or signs (1 Cor. 6:11, Phil. 3:3) Col, 2:9-12) and first committed to Paul.(1 Tim. 1:16).
So are they all the same? Or are they different as God's word to man progressed, so did His good news (Gospels)?
But there MUST be a thread that links them together. Something that, although each good news (gospel) is a further revelation from God, still resides in each one, even if it is not revealed at the time it is given. It is: the GOSPEL OF THE GRACE OF GOD. That was first committed to Paul. It is in THIS good news (gospel) that the summit of God's revelation resides.
How can we know this? "In the day when God shall judge the secrets of men by Jesus Christ ACCORDING TO MY GOSPEL." (Rom. 2:16). The "MY GOSPEL" is Paul's gospel. THis is where the Bible led up to and was and is and will always be. THIS GOSPEL, the GOOD NEWS that Christ died for our sins, was buried, and rose again the third day (1 Cor. 15:2-4); that "by grace are ye saved through faith, and that not of yourselves, it is the gift of God, not of works, lest any man should boast." (Eph. 2:8,9).
"For I am not ashamed of the gospel of Christ; for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith." Romans 1:16,17.