what is the different between while and when?

When 後面的句子裏的動詞很少用v+ing，while 後面的句子的動詞多數用v+ing.

例：I was running when the dog barked to me.
The dog barked to me while I was running.

While
noun
1. 一會兒,一段時間[S]
I'll be back in a while.
我一會兒就回來。
conjunction
1. 當...的時候,和...同時
She listened closely while he read the letter.
他讀信時,她聽得很仔細。
I'll take care of your children while you are away.
你不在時我會照顧你的孩子的。
We must strike while the iron is hot.
我們必須打鐵趁熱。
2. 而,然而
I like tea while she likes coffee.
我喜歡喝茶,而她喜歡喝咖啡。
3. 雖然,儘管
While I like the color of the hat, I do not like its shape.
雖然我喜歡這頂帽子的顏色,但我不喜歡它的形狀。
4. 只要
vt.
1. 消磨(時光),輕鬆地度過[(+away)]
He whiled away the whole afternoon watching TV.
他看電視消磨了一個下午。
When
ad.
1. (用作疑問副詞)什麼時候,何時
I'd like to know when they'll let him out.
我想知道他們什麼時候放他。
When did you last see Margaret?
你上一次見到瑪格麗特是什麼時候?
2. (用作關係副詞,引導關係子句)當...時
There were times when I didn't know what to do.
有些時候我不知道該怎麼辦才好。
conj.
1. 當...時
John got engaged to her when travelling last winter.
去年冬天旅行時,約翰與她訂了婚。
Don't get excited when you talk.
你說話時別激動。
2. 既然,考慮到
How can he get the promotion when his boss dislikes him?
既然上司不喜歡他,那他怎麼會獲得提升呢?
3. 雖然,然而
I had only fifteen dollars on me when the book I wanted cost twenty.
我身上只帶了十五元錢,可是我想買的那本書定價二十元。
4. 在那時,然後
pron.
1. 什麼時候,那時
Since when has she taught here?
她從什麼時候開始在這兒教書的?
n.
1. (事件發生的)時間[the S]