There are some people who think that crush and infatuation is the same thing. To a certain extent, this is true but there are some differences too. Having a crush on someone means that you admire the person. There is something about the person that makes you drawn to the person easily. Having an infatuation with someone means that you would like to know more about the person.
You want to find out more details about that person. The person is not merely a crush anymore. You are planning some things that will help you become closer to the person. When you have a crush, seeing the person is already enough to make you happy. When you are infatuated, you will feel happy after finding out more details about the one you like.