This table summarizes how I’ve been describing UK & US English differences about academic titles in my recent conversations about this with both Americans and Brits. I wonder if anyone reading this disagrees with my summary, beyond the fact that these are only approximate correlates, since the UK doesn’t have the tenure system that is so closely (but not completely) tied to the American distinction between Assistant and Associate. And there are other subtleties I’m glossing over, like the messiness of what “lecturer” means in the US, as well as things like the apparent distinction (at least at Oxford) between a post-doctoral researcher and a post-doctoral fellow, which is why I’ve just put “post-doc” here. Anyway, if you do disagree with this I’d be curious to know if it’s because of what part of the UK you’re in/from or if it depends on the university you’re at, or what.
Of course, there’s always Wikipedia: http://en.wikipedia.org/wiki/Academic_rank, which just goes to show you how overly simplistic my table is!