They're basically different programs of study. Check out the grad student manual on the department website and take a gander at the forms for planning your course load. Don't know what the breakdown will be this year, but admissions-wise it'll just determine which batch of folks you'll be up against in the consideration process, probably. TCS gets a couple (or has before) and literary studies gets a couple, too. My ethos: 5th year literary studies Ph.D. candidate at ol' P.U.