Here is where the difference between pardon and absolution ... just an example:
President grants "immunity" and "pardon" to all illegal aliens. Done deal ... president has that authority.
However, since existing laws remain ... the very next day, the illegal alien is still an illegal alien. Therefore, they are now guilty of committing a crime, as of today. Ergo ... still a criminal. Absolution, would continue to work against their continuing commission of crime(s) (such as being an illegal alien)
The president can only pardon someone (or group) of past crimes, not new crimes to be committed in perpetuity.