Sonny, welcome to EpicSki,
You will probably get 100 posts on this topic debating it, but the official definition that I work with is the retraction is an aggressive flexion. It sounds like your definition is similar. As JF says, they both regulate pressure, but a retraction does it much more actively or aggressively if you prefer. Both have their places in skiing and once learned are used impulsively as needed/wanted. Remember, that pressuring your skis is not all or nothing - there are various stages of pressure on the skis as there are various intensities that we could allow that pressure to change.