Convention over configuration is subclassing?

Having now played a little bit with Ruby on Rails, I am starting to wonder wether the much touted "convention over configuration" is really just a different implementation of subclassing. That is certainly what it felt like, and the Wikipedia article referenced states that "a developer only needs to specify unconventional aspects of the application."

Or perhaps slightly more accurately, both subclassing and convention over configuration would appear to be a form of programming by difference or "refinement".