A product owner in scrum is the development teams internal client.

A Product Manager could be a Product Owner but they also have a lot of additional responsibilities. a Product Manager is expected to achieve revenue, profit, growth, usage, customer satisfaction and retention goals by managing the products features and benefits, price, place it's provided, promotion, people, processes and the physical environment it is delivered in.

Product Managers and Product Owners have a different focus. Product Owners are focused on working with a scrum team to achieve the sprint goal. Product Managers are focused on integrating work across multiple teams and departments to create a desirable, viable and feasible product.