They work side by side, hand in hand, as part of an integrated marketing mix. They just differ in the type of content they create and how that content (and its impact on the audience) creates wealth for the business. Side note: In this definition, I deliberately use "customer" rather than "audience".
Customers are both buyers of our products and services, and audiences for interacting with brands, recommending brands, and more. I will explain in industry mailing list in this article. Practitioners of inbound marketing and content marketing have speculated for years that at some point these terms might not matter.
Conventional wisdom holds that both practices would only be considered "good marketing." HubSpot's evolution of inbound marketing into a broader practice may have been successful; in fact, it's been so successful that it's become the modern methodology for what our old-timers call "drop-shipping." However, I would argue that content marketing is still an evolving practice in marketing departments everywhere.