Difference between gem and event chest

well, what the thread says, i don’t get it beside the fact that event chest cost 5 gems more… is the event chest used in order to get old event cards like says, if i missed gob chomper there is a chance to still pull it on the event chest? what’s the whole point of the event chest?

Event chest are tight to the week’s event, so they give specific troops and stones.

so if i don’t care about pulling unit of a specific kingdom i should just buy gem chests?

That is correct.

Or save gems 'til there’s an event that gets you the units you want most.