Apple makes almost twice as much money as Microsoft does, but their valuations are similar. Thus the "market" believes that Microsoft's revenue is going to grow much faster than Apple's will.
As the article says, it appears to be the massive cloud revenue that has investors pumped. But much of that cloud revenue is probably Office 360, so is it really the type of cloud revenue people should be excited about? If it was categorized separately, I doubt investors would be so excited.
I suspect the answer is somewhere in the middle: Office revenue is a fairly mature business without the growth potential that AWS or Azure has, but Office 360 is a pretty powerful tool for Microsoft to use get companies to choose Azure over AWS.
Could Apple pull the same trick? Investors probably implicitly value App Store revenue as more likely to grow than hardware revenue so Apple could probably find ways to shift revenue from hardware to App Store. The next question is how much Apple cares about short term stock market shenanigans versus long term real growth. Apple employees hold a lot of RSU's so stock market shenanigans are well incentivized...