K
So I think you see that what Paul wrote was not written in the gospel but we can see the same Spirit of truth at work...
It may not be the same words that he uses, but still has the same meaning.
There is no change in meaning between what Paul was preaching, and what the Lord Jesus already preached. Just a difference in wording.
Just like you and me, if we each wrote an article on the same event we witnessed. The wording that both of us would use would be different, yet the meaning and the event will still be the same.
In the same since that at times saved, salvation, eternal life, and crown of life are all used for the same meaning and outcome.
And also eternal punishment, death, lake of fire, cut off, disqualified are all some of the words used to explain the outcome of willful sin.
Paul changed his wording a lot determining to who he was talking to at the time using things in that area that people were accustomed to so that they would understand what he was saying when it came to salvation and how to receive it. It did not change the meaning, just because he used different words.