这三个词都有目标、目的的意思,作名词解释时有以下不同：
Purpose是指做事情的目的,一个计划的目标、大方向.Goal是指比赛中的目标,比如该选手本次比赛的目的是要得到多少多少分,这里的“目的”就要用goal.Aim是指被攻击的目标,或者执行任务时精准的、明确的、单一的目标.
What is the purpose of his visit?
他来访的目的是什么?
purpose是指意图.
It is now our aim to set up a factory.
我们现在的目的是创办一座工厂.
My goal in life is to help others.
我的人生目标是帮助他人.
goal和aim的分别
Aim is often used in the sense of shooting at a target and refers to the accuracy of the shot as in:Aim an arrow at the board.Goal is very often an abstract concept for something you want to achieve and of course it is used in sports like football.
Another difference between goal and aim might be that goal is a noun whereas aim can be used as a noun as well as a verb.
goal通常比较抽象,aim则比较趋向一个比较specific的目标.
在运动比赛里,我们都用goal.
另外,goal 只能当作名词来用,而aim则可以是名词或动词.
It is now our aim to set up a factory.（名词）
We aim to set up a factory.（动词）