I looked on-line and found an answer from a social worker who is a hospital administrator at a teaching hospital. I hope this helps you.
Here's how she explains the difference:
The scope of practice is different, but there is overlap in that both clinical psychologists and clinical social workers do assessment and counseling. Practically speaking, both do individual, marital, and family counseling. Both have credentialing bodies with standards of practice and ethical codes.
Social workers may also work in community development, advocacy, and policy development. Psychologists can have specialized areas such as neuro, where, for example, they would set up programs in and/or consult in behavioral programs for acquired brain injury, or autism, or for testing for learning disabilities in adults and children, or for testing individuals prior to surgery for epilepsy, etc.
Only psychologists can diagnose and interpret standardized testing. Also, the education is different: Psychologists have PhDs and psychological associates have Master's degrees. Social workers have a BSW or MSW – a doctoral level of study is mostly for those involved in teaching and research.