Those who plead guilty can admit or fake remorse.  Those who don't plead, cannot.

Those who plead can partake in therapy.  Those who don't plead, cannot.

Those who plead can argue to a parole board that they've "improved" and can be released into the community.  Those who don't plead, cannot.

When there is no admission of guilt and the defendant's guilt is not clearly evident , you might hear, "He's in denial."    Denial is one of those buzz words used not only  to cover up a poor case for the prosecution but also to deny parole.   Of course, the conclusion of denial can only be a product of speculation . . . and should not be admitted into evidence whether or not an individual is deemed to be an "expert" for testimonial purposes, or at any other time before or after conviction.