Calvinist Disagreement with Valentinian Gnosticism on Predestination

For the record, I do not believe Calvinists are cryto-Valentinians. I do not believe Calvinists are Gnostics, so please understand my question knowing I am not trying to paint anyone in a good or bad light. **What specific beliefs do Calvinists (or proto-Calvinists like Augustinians) specifically take issue with in Valentinian's predestinarian system?** So far, I've only been able to find that the Valentinians believed there were three different classes of men with different natures. I believe Calvinists teach that the saved and the damned have the same human nature, but I'm not sure.