Although the expertise of Product Owner and Project Manager is to par, the roles they play are focused in different phases of the project lifecycle. In most cases, a Product Owner identifies the expectations of the stakeholders and it's their responsibility to ensure that the product is maximizing its potential value. They concentrate on the requirements, oversee the product backlog, and guarantee the direction is towards the set business objectives. Concernedly, however, Project Managers watch the execution progress, making sure the project is completed on time without exceeding the budget or the scope. They function as a hub of communication, organize resources, mitigate risks in the operations, and make sure every team member is in sync. In case you want a minute by minute break down of their differences, do not hesitate to go through this article
here.