How to differentiate MacBook Air from MacBook Pro in Chinese?
It is okay to say Macbook Air in between Chinese, or you can say 苹果的Air电脑 or 苹果的Air系列电脑 if you must. More info:


It seems that mainland Chinese are adapting 电脑, but I want to point out both 電腦(traditional Chinese) and 计算机(simplified Chinese) means "computer". 電腦 is used everywhere while 计算机 is only for formal use in mainland China. (計算機/计算机 can mean "calculator" in other scenario, so 电子计算机/电脑 is used to differentiate.) (referecne)
Macintosh = 麦金塔电脑 or simply 麦金塔 in Mainland China. In HK, we called it Mac機. (reference) 苹果的电脑 only means computer from Apple.
Japanese have Katakana , but Chinese don't.
As you may know, in Chinese we say a laptop/notebook computer 筆記本電腦/笔记本电脑 but we do not translate the Air into 空
I don't know any nicknames for Macbook Air yet like iphone 爱疯 though.