[tomflack]

Apple didn't always have a low market share and built up a huge importance for developers before their share started to slide.

There are still millions of iPhones sold every year, even if they're a smaller piece of the overall pie.

Contrast to Windows Phone which never had any kind of market share or importance, and has to fight up from absolutely nothing.

That's the difference between iPhone's small market share and WP's small share.

[MaysonL]

Actually, Apple's share of the mobile phone market is still growing, as it has been since 2007. It just isn't growing as fast as Android's.

[tomflack]

Market share vs units sold. One is sliding down (market share) while units sold are still going up as the pie gets larger.

[mikeash]

I'd say the difference is that Apple's share, while smaller than Android, is still large. Apple is selling huge quantities of devices and making huge quantities of cash from it. Windows Phone is doing neither.