Well, you need to be more specific about which type of ProRes you want to compare to DNxHD, but I'll take a guess at what you meant and try to answer.
There isn't always DNxHD variant directly comparable to ProRes 422, because ProRes 422 is always 10-bit and DNxHD is 8-bit in low to mid bitrates and 8-bit or 10-bit at high bitrates.
There are some variants of both that match up almost perfectly. ProRes 422HQ and DNxHD 175X, 185X, 220X are directly comparable as they are all 10-bit 422 codecs with a very similar bitrate.
5 minutes on wikipedia would really help you understand. Don't be so damn lazy.
http://en.wikipedia.org/wiki/DNxHD_codechttp://en.wikipedia.org/wiki/ProRes