I want to pick this fight again. It's not over yet, and IMHO, we have not yet cracked the nut fully. I still see, hear, feel - sense - a lot of confusion over what people mean when they use these seemingly similar terms to define things that are often at odds with each other, and are driven in different ways out of necessity.
Is user experience a road trip and usability the road and signs? This was one of the metaphors provided in some posts a couple years ago on Interaction by Design. I am not sure it was ever properly solved in the post or resulting comments, but it never got to customer experience anyway. Suffice to say that the confusion stems from the fact that there is already confusion over what people mean by user experience.
Let me try it a different way - in relation to a software company selling software. User experience is what happens in the software. Customer experience is what happens when the user purchases the software. This may oversimplify the outcomes but it does clearly delineate the differing responsibilities of the various teams involved. Developers, usability experts, scenario testers, interface designers plug themselves into the software development process and arrive at the desired state - the world's leading illustration software example. But it doesn't sell itself, now we have to sell it.
So, now we take the information we have from that user experience and begin to define a marketing campaign, website, training, tools and more to entice potential users to come and see how great the user experience is. In my fleeting thesis, this would be the customer experience. A whole new set of usability challenges ensue, but now related to websites, ecommerce, community, online support, training, etc...hopefully handled in way that effectively set realistic expectations about what the user experience would be.
We can't sell ice to eskimos...that was some other department that was trying to do that. Not sure but I think they were all laid off. But let's explore that for a second. The user experience for the ice is based on the fact that it is cold, hard, made up of water, useful for types of construction, food storage and more. The customer experience is all about going to the cold place, cutting the blocks, or maybe just stopping by your local gas station to get a bag. In this last example the user and customer experiences are actually pretty disconnected, as it normally would be from a retail perspective. I don't want the gas station to be frozen, clear, made of water or to preserve my food (I guess gas stations all sell food now though) - and I don't want my ice to have any fuel content, or be branded with little seashells.
One thing I think we can all agree on, is that when it comes to customer experience, the only true owner is the customer. While it is going to take a lot of x-functional effort to make a great customer experience, the customer is going to point it all back at one thing - the customer environment. With user experience, it is also owned by the user, but there is a more clearly established set of rules, goals, sciences and legacy knowledge we can draw on in order to define that part of the road.
I will continue this by providing more interesting, humorous and embarassing examples of each in order to keep track of my thoughts on this...you can follow along over the ensuing days and weeks and that will be your customer experience, or click, search or nav your way elsewhere as part of your user experience. You decide.