Calling it "therapeutic massage" was part of a the professionalization of massage therapy. It is a way to communicate that this was a massage for health, and that no sexual contact was involved.
Today, any professional massage is therapeutic, with real health benefits. But the phrase "therapeutic massage" is also sometimes used to indicate that the massage will be a little more intense than a pure relaxation massage and perhaps deal with long-term or chronic issues. The most common examples would be a deep tissue massage or sports massage. The therapist uses more pressure and cross-fiber friction in order to get knots (also known as adhesions) to release.