Deadlift vs. Sumo Deadlift
Looking at the deadlift from the ‘functional’, everyday side of things, when picking something up off the ground, our feet are generally wide and our hands/arms are in side of them, unlike the position of a conventional deadlift. The definition of a sumo deadlift is a deadlift where the feet are on the outside, and the hands are on the inside. Typically a taller lifter will have a wider stance to make up for their longer limbs, while a shorter lifter will choose a narrower stance. If you have tight hips when starting sumo, you will be better off with a narrow stance. As you become accustomed to sumo, you edge your feet out more and more to find where you can move the most amount of weight.
Once the width of your stance is set, you want to fan your toes out much more than you normally would on a conventional deadlift. The reason for pointing your toes out so much is you want to drive the knees out hard.
Driving the knees out, or “spreading the floor” will help you break the floor by activating your glutes more.