[CMake] What's the difference between option and variable of type bool

[Marcel Loose]

Hi all,

I feel rather stupid, but I fail to see whether there's any difference
between a CMake option (which is stored in the cache as a variable of
type bool) and a CMake variable of type bool that's being cached.
Both can be modified in a GUI like ccmake.

Is there any reason to prefer the former over the latter?

Best regards,
Marcel Loose.