The spec published by WHATWG is a living standard, and is just called "HTML". The expectation is that every so often the W3C will pick a revision of the WHATWG's HTML spec and stamp it with a version number.
> The expectation is that every so often the W3C will pick a revision of the WHATWG's HTML spec and stamp it with a version number.
W3C HTML5 is not just a snapshot of a particular revision of the WHATWG Living Standard. In a reasonable world, W3C HTML5 (etc.) would be a subset of the WHATWG Living Standard on the date the former was published, but I'm not sure that even that is strictly the case.
Well, this announcement seems to indicate that from W3C's point of view, it's not living anymore. They've finalized the standard, and are starting work on HTML 5.1. WHATWG apparently no longer numbers their standard. [1]