What are the differences between「目的」and 「目標」?

Question

Both「目的」and「目標」have a common meaning which is "goal", but what is the difference?
When can we use one but not the other?

Answer 1

目的 can also mean "purpose". There is a book called "The Purpose Driven Life". In Japanese, it's titled 人生を導く５つの目的.

I think it boils down to the difference in English between "purpose" and "goal". A goal is something finite you hope to achieve. A purpose is like a motivation for why you do something. Often they will overlap, but not always. Having a finite goal kind of implies that you have a motivation. However, the converse -- having a motivation implies you have a finite goal -- is not necessarily true.

Ex.

A: Why did you come to campus today?
B1: I came to visit my professor and get a letter of recommendation. → The goal and the motivation are the same: get the letter.
B2: I came to visit my professor. →　The motivation of why I came to campus is to see my professor. However, there is nothing "achievable" just by visiting him.

So the same with the Japanese words. If you have a 目標 you also (likely) have a 目的. However, if you have a 目的, you do not necessary have a 目標.

That's how I see them anyway.

Answer 2

目的＝目標＋意味

I would think of a basic example.

I want to become better at shooting the basketball. => 目的
I will consider myself better at it when I score at least 50% of my shots. => 目標

I think 目的 is a high level image, global image of a goal. 目標 is more achievement like low level goal, usual can be quantified and explicit that will define the concrete steps to the 目的.