Answer 1

Android is a mobile O/S, window is part of a building. Without a window a building is sealed off sunshine, causing the building to be cold and less hygiene (higher bacteria growth rates), and the building will cost more on lighting and air conditioning.

Answer 2

Right, but even adding an 's' behind the word 'window' can still lead to diferent meaning or misunderstanding : )

Answer 3

It's also common misunderstood.

Answer 4

Android - Linux OS for most of the mobile devices on earth
Windows - OS for PC and most of the Laptops on earth.