他們有的***同含義是意願。而will還有意誌，更傾向於壹個信念。
其實學英語不要太苛求於詞的分別，可以通過記憶例句來比較理解。
這才是最地道的。
另外這兩個詞都可以壹起用的啊。
It is not something that you can do through any effort, will or volition of yours.
這不是妳可以通過任何努力和意誌能做到的。
附兩個詞的柯林斯詞典詳解：
volition /v?ln/
1.N-UNCOUNT Your volition is the power you have to decide something for yourself. 自願選擇; 自行決定
例：
We like to think that everything we do and everything we think is a product of our volition.
我們願意認為我們所做和所想的壹切都是出於自己的意願。
2.PHRASE If you do something of your own volition, you do it because you have decided for yourself that you will do it and not because someone else has told you to do it. 出於自願
例：
Makin said Mr. Coombes had gone to the police of his own volition.
梅金說庫姆斯先生是自己主動去投案的。
will（名詞）
1.N-VAR Will is the determination to do something. 意誌
例：
He was said to have lost his will to live.
據說他已經喪失了活下去的意誌。
3.N-SING If something is the will of a person or group of people with authority, they want it to happen. 意願
例：
He has submitted himself to the will of God.
他已經讓自己聽從上帝的意旨。