What is the difference between salvation and being born again?
There is essentially no difference between being born again and salvation. The phrase “born again” only appears in two passages in the New Testament. The first is in John 4. There, Jesus tells Nicodemus that in order to see the kingdom of heaven he must be born again “of water and spirit.” Since the kingdom is the church, and the church is made up of the saved, then being born again would be the same as being saved.
The other passage that mentions being born again is 1 Peter 1:22-23. “Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently: Being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth for ever.” Peter equates being born again with purifying our souls. Since the purification of the soul would be forgiveness of sin, then being born again is, in Peter’s view, the same as salvation.
Paul doesn’t use the phrase in Romans 6, but he talks about the concept. In that chapter he says that those who have been immersed (in water) have been raised to walk a new life. If it is a new life, then the process of entering the new life (baptism for the forgiveness of sins) is the same as a new birth.