For simple minded people like you, Enma is a gattling gun that fires more bullets faster than a pistol. Except here the bullets are haki and haki is dormant in most people
It simply draws out haki on its own- more than intended and whatnot. It's a training tool- if Zoro can control Enma's draw, then that means he has much better control over his CoA release and can adjust it accordingly and release lots of it more quickly across all his swords.
You can't compare firing bullets to coating your sword in uniform amount of energy fluid or w/e lol