MSW: Master of Social Work. In Ontario, MSW is the most common designation of therapists - and it's also the most commonly covered by benefits. John got his MSW from Wilfrid Laurier University in Waterloo, and in it he specialized in clinical counselling practice with individuals, families, and groups.
MDiv: Master of Divinity. Having this degree means John can cast awesome spells and conjure animals to help him do things. Just kidding. It's a degree that focuses on the existential/spiritual aspects of counselling. John got his MDiv from Laurier in Waterloo, and in it he specialized in spiritual care and psychotherapy.
RSW: Registered Social Worker. Being an RSW means John is a member in good standing with the Ontario College of Social Workers and Social Service Workers (OCSWSSW). This means that 1) most insurance companies will cover you to see him, 2) he meets the ethical and professional development requirements of the College.