You can't compare apples and oranges.

苹果和橙一也不象，是没法比的。

youdao

EXAMPLE: Truck sales and automobile sales are apples and oranges –you can't compare them to understand consumer behavior because trucks and car are purchased for very different purposes.

卡车销售与汽车销售是两件看上去相似但实际上根本不同的事情——我们不能为了解消费者行为而将它们对比，因为人们购买卡车和轿车是出于完全不同的目的。

youdao

Example: You can't compare who works harder, me or you; I am a teacher and you are a fisherman, and that is like comparing apples and oranges.

例句：我和你谁工作更努力不能拿来比较，我是老师，而你是新生，根本风马牛不相及。

youdao

To crowd Lewinsky and Rwanda into the same viewfinder is not just to discuss apples and oranges but to compare, forgive me, apples and severed heads.

CNN: Rwandan tragedy, Lewinsky farce

It is very true that our experience, leadership, dedication, loyalty and the countless other personal attributes that were honed in the line of duty count for something and are desired traits from all employees and that you will never be able to fairly compare apples to oranges(military to civilian), but those are what they are, character traits!

FORBES: Veterans Make Valuable Employees, So Why Aren't More Getting Hired?