What is the difference between symbian os and windows os?

Android and Symbian are both open-sourced OS. Symbian at the time was the most popular mobile OS worldwide (Nokia being its biggest proponent) until Android surpassed it around 2011. Part of Symbian's fall was that much of its licensed source code was restricted to only member companies. In comparison, Android's licensed source code is relatively free of restrictions, which helped spur its use among manufacturers, carriers, and the developer community.