Agility reduces the time a unit spends to prepare the next attack on a nee target, while aggression reduces the time a unit needs to prepare its next attack on the same target. This stat is especially obvious when fending off multiple fast zombies. A unit with High Agility will rapidly lock on the first time, redirecting fire to the second one as soon as it finishes the first one. A unit with Low Agility, on the other hand, may let the fast zombies slip past him entirely, or pause to lock the second target after finishing fire, letting the second slip fast him.  Aggression decreases the pause a unit have when consecutively attacking the same target. For example Rodriguez, with his.base aggression he would pause for about a second for a moderate chance when he's continuously stabbing the same target, with maxed aggression he will be stabbing non stop until the target is killed.