The word aim and purpose can act as a noun and also as a verb. These words are synonyms of each other in which both words mean that an object intended to be obtained or simply an intention.
Aim means pointing a weapon in the line of direction with the object intended to be struck or aim can also be defined as the ability of someone to aim straight one faculty for being able to hit a physical target. The word aim answers the question of what. Purpose can be simply defined as an object to be reached, or the reason for which something is done in a particular way; for example, some people exercise just to lose fat. That is the purpose of going to the gym house is to burn fat. The purpose is way deeper than the aim. Purpose answers the question of why.
Some may assume that aim and purpose are the same. You should realize that they are not completely the same. When you say aim, this is something that you would like to achieve. For example, you may “aim” for high grades. This means that you will do different things that will make it necessary for you to get the grades that you want.
When you say “purpose,” this may refer to something deeper. Your purpose for getting high grades is to probably get a scholarship to a college/university of your choice. Your high grades will improve the chances and the possibilities that you will be chosen.