low vs oom
Which resource is missing. "low" is health; "oom" is mana. Both say a player cannot fight anymore, but not for the same reason, and not with the same consequences.
low
Low is low hp: the health bar is down. Said of yourself, it refuses a fight or announces a recall. Said of an enemy, it is a call to finish them: "mid low go". A low player dies to the next spell that lands.
open the page →oom
Oom, out of mana: no mana, so no spells. An oom player has all their health but can neither defend nor attack, and an oom enemy is a target: "he is oom go". For a marksman it barely matters; for a mage it ends the lane.
open the page →Why they get mixed up
Both get typed at the same moment, when fighting is no longer possible, and both call for the same answer from the enemy: engage. But a low player can still cast the one spell that turns a fight, an oom player cannot cast anything at all. That is why "he is oom" is worth more than "he is low" on a mage.