what did the two men's opinions differ on revealing of sins?

I think you are referring to Dimmesdale and Chillingworth. Dimmesdale trusts no man and is unable to reveal his sins to a curious Chillingworth. Chillingworth is going all psychoanalytical on Dimmesdale. He tells Dimmesdale that his secret sins are relevant to his health. Dimmesdale says his sins are between God and himself.