In The product owner and the product-shaped hole, Jeff Patton writes:
Product owners learn lots of agile process but scant product design and product management practice
In our work in Living in an Agile World, we've seen product managers struggle with the role of the product owner. Jeff does a good job of describing his view of the role. Call it product owner or product manager or technical product manager, it all comes to the same thing: vendor products need a market-based view of the product, not just a prioritized backlog.
Product management is a comprehensive role that covers strategy, technology, and marketing as defined by the Pragmatic Marketing Framework.