I use these on my layout. A block is just an electrical partition of the track. The power is usually on if you are running command (Legacy/TMCC or DCS or LionChief). If running conventional, you may want to use some kind of selector switch to choose between multiple throttles.
A stop block is a track segment that is controlled by an on/off switch, so you can kill power to it.
I think that's what you're referring to anyway.