The difference of four words: mission, purpose, goal, aim 1) definition(Macmillian) mission: a goal that is very important to a person or organization purpose: the goal that someone wants to achieve, or that sth is intended to achieve goal: sth that you hope to achieve aim: the thing that you hope to achieve by doing sth 2) nuance The degree of strong desire is as follows: goal < aim < purpose And the most important target among the words is "mission" (Source - written in Japanese http://wakaruenglish.shinyblue.org/mission%E3%81%A8purpose%E3%81%A8goal%E3%81%A8aim%E3%81%AE%E9%81%95%E3%81%84.html )

Purpose is the reason for doing something or for existing. Goal is what you are trying to achieve, where you are trying to get to. When joining this website, my purpose was to meet with speakers of Thai. My goal is to speak Thai well.

"Goal" has several meanings, and can mean a physical goal (in football), the fact that someone has scored a goal (suceeded), or desired success in a competition (figurative meaning). "Purpose" is immaterial and abstract. It's only your intention. The meanings of "purpose" and "goal" only overlap in business English.