The difference between a perfect man and an imperfect man is that the perfect man does not have a weakness for sin. In order to sin against God, a perfect man's sin has to be deliberate. This one would not have the struggle that Paul described at Romans 7:13-25. Where there is deliberate sin, there is no forgiveness left for that one.
"For if we practice sin willfully after having received the accurate knowledge of the truth, there is no longer any sacrifice for sins left, but there is a certain fearful expectation of judgement and a burning indignation that is going to consume those in opposition." - Hebrews 10:26,27
Did Adam have an "accurate knowledge of the truth"?
"Also, Adam was not deceived." - 1 Timothy 2:14a
"Nevertheless, death ruled as king from Adam down to Moses, even over those who had not sinned in the same way that Adam transgressed, who bears a resemblance to the one who was to come." - Roman 5:14
What is the distinction? Adam's sin, being deliberate in the face of accurate knowledge, incurs death with no hope of restorable life.
"If anyone catches sight of his brother committing a sin that does not incur death, he will ask, and God will give life to him, yes, to those not committing sin that incurs death. There is a sin that does incur death. It is concerning that sin that I do not tell him to make request. All unrighteousness is sin, and yet there is a sin that does not incur death." - 1 John 5:16,17