What is the difference between competetive and non-competetive inhibitors?

Competetive inhibitors are the same shape as the enzyme substrate. They bind directly to the active site of the enzyme, preventing the binding of the substrate. Therefore, if you increase the concentration of the substrate, there is more chance that the enzyme will bind to the substrate, increasing the rate of reaction until you reach Vmax.

Non-competetive inhibitors bind to a different part of the enzyme, changing the shape of the active site. this prevents binding of the substrate to the active site. therefore, it doesnt matter how much more substrate you add, the rate of reaction will never be the same as without substrate, becuase the non-competetive inhibitor will always be free to bind to another part of the enzyme.