What is the difference between Delaware and Pennsylvania mint?

the sate quarter collection has 2 types of quarters. D and P. I wonder what is the difference between these 2 mints?

What is the difference between Delaware and Pennsylvania mint?
Actually, the answer is as one of your answers said,..."denver" and "philidelphia".....but, the philidelphia mint doesnt mean a coin was made in phildlphia it can also mean that it was in certain cases, "minted at westpoint" where there is another us mint. the san fransico mint "s"...which doesnt mint currecy coins amymore does make the dyes for currency coins and it makes "proof coins which display the "s" on the coin. the coin collecting industry can give you more information on this and you can contact the "US mint" for more information.
Reply:Nothing other than physical location.
Reply:Me thinks you Mean the difference in Denver and Philadelphia mint..about 25% of coins are made in the Denver mint,other 75% are made in Philadelphia