A draper header uses sickles for cutting the crop and the crop is moved to the middle of the header using the draper belts. A auger header is the same but uses an auger instead of the draper belts to move the crop to the center of the header to form a windrow. Draper heads are most common for grain cutting and auger heads are for hay. A disk head is for cutting hay only....takes lots of hp but you can cover lots of ground quick and they are very simple to maintain. Disk heads as well as sickle/auger heads will have hay conditioners on them. We use a 13ft disk head for cutting hay to bale and a 35ft draper head for silage.....the 35ft is a grain head but works to cut hay ahead of a forage harvester.