What is the difference between non competitive and competitive inhibitors?

Competative inhibitors bind with the enzyme at the active site, blocking the substrate from binding and therefor preventing the substrate from binding and forming enzyme substrate complexes. Therefor if you increase the concentration of substrate you can increase the reaction rate as the substrate competes with the inhibitor for the binding site.

Non-competative inhibitors however bind to the enzyme away from the active site, changing the shape of the active site so the substrate cant bind. This cannot be overcome by an increase in concentration of substrate.