By far the easiest (and probably most over-cited, please forgive me) to distinguish these two comes on lauded usability expert Jakob Nielsen's homepage, useit.com. Jakob has dedicated a lifetime to the study of usability, and his website represents a page that is extremely easy to interact with. Everything is front and center, easily searchable, with important ideas stressed through bold text. Yet despite its high level of usability, the lack of interesting layout, design, or even typography makes the site rather boring and feel uninspired. I can accomplish my goals here easily, but I probably won't have much fun in the process.
A nice write up and examples on how usability differs from user experience. That said, while these are 2 different professional disciplines, keep in mind that users don't make a difference. They enjoy or don't enjoy using your site and that's really the end result a product manager will strive for.