Political theory and political philosophy: as promised, Jacob Levy has some comments on the difference between them and what causes it.
Update: Russell Arben Fox comments on Levy here. I hope to have something to say about this eventually, but it'll have to wait a little while.
Update (2): Then again, maybe I won't have anything more to say. I don't have much to add to what Tom Runnacles says about learning analytic moral and political philosophy in Oxford. Though I will say that you'd probably have a slightly different perspective if you studied politics or political philosophy with people like Mark Philp, Larry Siedentop, Michael Rosen, Stephen Mulhall, Michael Freeden, or Elizabeth Frazer.
Update (3): Larry Solum has a nice round-up of links related to this topic, available here.