The inventors of XP wrote down what they were saying verbally, and they said OAOO. Then the ThePragmaticProgrammers thought of an awesome acronym for it. "DRY" is very easy to say, and it fits perfectly in writing. "I need to dry that module up next".
They are the same thing.
Definitions given on each page:
DontRepeatYourselfEvery piece of knowledge must have a single, unambiguous, authoritative representation within a system