The difference is two letters. Seriously though, there are plenty of online dictionaries and resources that could more conveniently and immediately answer your question. Personally, they seem quite interchangeable, except for individualism seeming broader and more conceptual to me somehow, while individuality seems to refer more directly to the individual. That's just me though. A matter of qualia. Good luck.
Individuality is something that everybody has. Individualism is an ideology to which not everybody subscribes.
