An operating system manages a device's hardware resources and provides the environment in which applications run. A television, phone and computer can use different systems even when they share a brand or screen size. App availability, installation methods and supported settings depend on that environment and its version, not just on the device's marketing name.
A practical example
An Android phone app cannot be assumed to install on a television using another operating system. The viewer needs software distributed for the actual platform, with controls and media support suitable for that device's intended viewing arrangement.
A common misunderstanding
Do not describe every smart television as Android or treat all models from one manufacturer as identical. Confirm the platform and model before following installation or settings instructions.
Related terms
Stable technical definition. Editorial approach