I don't think there's a real clear definition of "emergency", but in general it refers to "being fed from a generator, as well as from normal power"
So, all things considered you would have two types of emergency circuits:
1: Life safety (as the name implies it, it regards life matters. In most situations it's egress lighting, elevators that can be used by firefighters, etc) A fire pump falls under same type. Might be wrong, but I think they are called "legally required standby"
2: Optional standby. This would be like a cooler where the customer doesn't want the food to spoil while power is out.
In general optional standby can not be fed from the same generator as the legally required. There's one exception. If the system can be programmed where the optional standby can automatically shut down if the generator is getting overloaded.
Just curious....when it says "all life safety circuits" are those circuits feed from EM panels. I KNOW it would NOT be norm power panels but was thinking it might be specific EM panels possibly. THis is regarding lighting/general power? THanks.