Why is the orchestra version of hungarian rhapsody 2 played 1 half step lower than the piano version?

Without actually seeing what keys they are in, I would have to guess to make the key easier. Let's say the piano version is in Eb, this is a pretty easy key for pianists but would be harder for strings who aren't used to playing in flat keys. It being a half step lower in D would make it much more comfortable for an orchestra.