I've completed the SAFe certification for PO/PM and this is one of the topics covered over there. SAFe clearly states that a Product Owner reports to a Product Manager.
Essentially, the PM is the person who interacts directly with Business, creates the Product Roadmap and drives the PI level objectives. However, the PO interacts directly with only the PM, works directly with the Scrum Teams, and drives sprint level objectives. These are the main differences. If you are interested, you can also check out my additional thoughts on this topic.