MSW

A Master of Social Work is a credential that you will often see for counsellors/therapists and is a good couple of letters to notice as many extended health care plans will cover sessions with an MSW. 

It is good to know that social workers are unable to provide a mental health diagnosis or prescribe medication. However, social workers are trained in issues around mental health, so if your therapist suspects that a formal diagnosis or medication might be helpful to you, they would refer you to a psychiatrist.

RSW

A Registered Social Worker is registered with the Ontario College of Social Workers and Social Service Workers (OCSWSSW), which is a regulatory body that ensures ethical practice and protects the public interest. If you ever have a concern about a social worker's behaviour, this is who you would reach out to for support.

Coverage

If you have extended health benefits, review your plan as most insurance providers cover sessions with an MSW, RSW.  

If you do not have extended health benefits, working with a Registered Social Worker means that you might be able to claim sessions as part of your medical expenses.