The difference is arod, clemens, and even pettitte have been proven to be liars...so we are skeptical when Pettitte says 'i only did it once, or twice' (i forget which once he landed on) and arod says i only did it from 01-03. History tells us that they have been dishonest when it comes to their history with PED's, so we have a right to be skeptical.
If Ortiz is proven to be guilty of using PED's then he will be hammered here as well. Do I think it's possible he used, yes...but I will reserve judgment until he has been proven to have used. Bringing up an old article, where he talks about things he did in his youth and comparing it to the current situation is just foolishness.