Surface Pro versus MacBook Air: Who's being dishonest with storage space?

I’ve done the cold, hard math of looking at disk storage for both devices. Here’s the story, in a single picture:


Wait a minute, I can hear you saying. Those bars look remarkably similar. And in fact, the Surface Pro actually has MORE free disk space for user data in one of those bars than the MacBook Pro.

Yes, that’s true.

Here’s the tl;dr version. The MacBook Air 128 gives you 77.3 percent of the advertised storage space for user data. The Surface Pro 128 gives you 75.2 percent of its advertised capacity for storing data. And with one minor tweak that doesn’t affect the system’s capabilities in any way, you can increase the amount of data storage space on the Surface Pro to 81.8% of the advertised capacity.

Ed Bott in a fine piece of investigative journalism reveals the truth about storage space in similar capacity Surface Pro and MacBook Air. Now I wonder why such an analysis did not come out from Windows team?