Will the relationship between the smart phone software development platform and smartphone operating system?

            


We know that a feature of smart phones is to have a smart phone operating system. The information found in front of said mobile software development platform is located above the mobile operating system that layer structure. So I would like to ask the relationship with the phone software development platform Symbian mobile operating system, for example, and Windows Mobile, can it be said is a software development platform? In addition, brew in the end is a software development platform or operating system?
brew with Symbian difference in where?

Currently looking at this, for these very confused, it helps me look together to discuss, thank you.
Reply:
Symbian and Windows Mobile is os, brew a development platform, not os