If you plan to make massage a long-term, formal career, the difference between "RMT" and "ordinary massage practitioner" may decide your income sources and career ceiling.
Regulation: regulated vs. not
This is the most fundamental difference. An RMT is a CMTO-regulated health professional, bound by standards of practice, a code of conduct and ongoing quality assurance.
An ordinary massage practitioner (e.g. offering relaxation-only massage) is not a regulated health profession and may not use the protected title "RMT / Registered Massage Therapist".
Training: accredited vs. no set standard
To become an RMT you must complete an accredited program (typically over 2,000 hours) and pass CMTO's certification exams. Training covers anatomy, physiology, pathology, assessment and clinical practice.
Ordinary massage services have no such mandatory, standardized training and exam threshold, and training quality and length vary widely.
Practice: assess & treat vs. relaxation
An RMT's focus is assessing and treating musculoskeletal issues — targeted treatment for pain, injury or limited movement, with professional documentation.
Ordinary relaxation massage mostly provides a soothing experience and does not involve health-profession assessment or treatment.
The key insurance difference
For clients, a very practical difference: in Ontario, many extended health plans only reimburse receipts issued by an RMT. That's why "is this an RMT" matters to clients and practitioners alike.
In one sentence: RMT = a regulated, accredited, insurance-eligible registered profession; ordinary massage = a service not regulated as a health profession. If you want a formal, sustainable career path, RMT is the one worth investing the time to train for.