The difference in the two Gospels is that the first from Peter to the Jews stresses repentance and baptism.
Acts2:38
KJV
38 Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.
Paul stresses the death burial and resurrection of Jesus.
1 Corinthians 15:1-4
KJV
1 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand;
2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain.
3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;
4 And that he was buried, and that he rose again the third day according to the scriptures:
Here there are two different approaches to salvation; one given by Peter and one by Paul constituting two different gospels, one for the Jew, one for the Gentile.
The problem is that you are pitting Acts 2 against I Cor. 15. Both are equally valid gospel truths if you interpret them right.
It is a MAD myth that Acts 2 does not teach the person and work of Christ, including His death and resurrection, faith, etc.
The way MAD understands baptism, repentance, etc. is not biblical. We give verses from a Pauline perspective on this, but the lights don't seem to go on.
United Pentecostal Church proof texts Acts 2:38 as the gospel and insist on baptism in the name of Jesus only (vs trinity), repentance with legalisms, speaking in tongues as salvific, etc. Proper exegesis of the verse does not support their view nor MAD's.
Grammatically, repentance, not baptism, is linked with remission (parenthetical issue in the original also). Understanding the relationship between water baptism as a practice in the early church and the condition of faith is important. You are importing a wrong assumption onto the text. It does not support your two gospel theory.
The same problems arise with Lord's Supper/Communion. MAD is wrong in what it says about I Cor. 11, a Pauline passage.
MAD is based on ignorance of sound NT theology/exegesis.
Please revisit it critically vs gullibly.