Spawning particle systems vs Activating

So I was wondering, is it normally best practice to spawn a particle system when an event is triggered using the “spawn emitter” function, or is it best to use the “activate” function. This is considering my effect is a burst emitter.

Also does it work differently in Niagara since it seems the function is called “spawn system” rather than “spawn emitter”? Does this mean I can attach one Niagara system to my player and have it store all the emitters and only play ones I pick?

Normally what is most performant? Are my particles automatically pooled by UE4? if so, is spawning vs having it constantly existing a better option?