(1)Some people waste food while others haven’t enough.

一些人糟蹋食物而另一些人却食不果腹。

解析：while为并列连词引导2个并列句表示一种“对比关系”

The first two services are free, while the third costs £35.00. 前两项服务免费，但是第三项服务要花35英镑。

Motion is absolute while stagnation is relative.
运动是绝对的,而静止是相对的。

(2)We must strike while the iron is hot.

我们要趁热打铁。

解析：while为连词引导时间状语从句，表示“在...期间”用来描述主句动作发生/主句状态存在于从句所表示的整个时间范围之内。而且while引导从句必须为持续性动词或者状态动词。

I lived in a hostel while I was a student.
我求学期间住在青年招待所里。

While Mary was writing a letter, the children were playing outside.
玛丽写信时，孩子们在外面玩耍。

备注：while还可以引导让步状语从句，相当于连词“though/although”

While I admit his good point,I can see his shortcomings.
虽然我承认他的优点,我还是能看到他的缺点。