For a while, I toyed with the idea of combining these two for a nice double-major. People back home thought I was crazy: "Aren't they pretty much the same thing??!" Nope.
In the end, I stuck with one of them, but the two are very different (as knat and SN pointed out).
Also, PubPol has its own school now, just like the NSOE or Pratt. I like to call it "The SIPP"