ccnp = four tests. (Routing, Switching, Remote Access, Troubleshooting) Thats easiest method...although you could do one super hard test (Foundation Routing and Switching) + Troubleshooting. Its basically ccna with more depth. Very easy.
CCDP = one test. (CID test) Once you do your CCNP you will know most of the info to pass this test. Just review with a book once and you should be fine!
Good Luck!
-M.T.O