Discrepancy means a disagreement with something and a discrepant would be someone who is disagreeing with something whether written or being said.
Also if someone has filled out some paperwork and they say there's a discrepancy it means that they disagree with what was filed in the paperwork and that something that should match up doesn't.
So like I said above a discrepant would be the person who has the discrepancy or disagreement with what's written or being said.