To keep it simple: imagine a time where the internet didn’t exist, and you could interface a microcontroller with a screen. The screen displays whatever you want from the microcontroller and you can control them both ways.
Now, imagine there’s internet, and in addition to the above, you can do all things internet related.
Now, imagine being able to cater for both scenerios where you don’t have to change your hardware, software and development.
One device to control the project that could connect to the internet in addition to its offline performance. (In this case, connected is preferred, but offline functionality is still possible without having to change the entire project)
It doesn’t have to connect to the cloud for it to be functional. So in this case, it’s ‘just’ a regular non-connected Microcontroller.