First, I’d like to know why the numbers are so different.
Why do numerous articles say that Android is first, Apple second and Nokia third?
Not my words ... but why do other articles state this?
What articles state that? They show Nokia leading mobile devices and cell phones. Everyone - including your own sources - states as much.
There are more total iPhones installed as compared to Android, but Android has now started outselling iPhones, so it won’t be too long before there are more Android phones than iPhones.
The numbers are consistent - Nokia leads, Android has overtaken sales from Apple, and Apple is losing market share, predominantly to Android (and a slightly resurgent BlackBerry).