Its simple really. Some stuff drops only on normal mode. Some only on hard. If u skip normal after reset and go right the hard ( most ppl) u get the normal drops with the hard drops. Just not the normal mode loot table. Crota is dif from vog. Vog u can get everything u can on normal, and then some. And if u skip norm, and go right to hard, you will get Double loot rolls ( yes exotic chest gives shards with the exotic instead of one or the other) and double loot rolls from the hard mode loot table. Example. Other day i got 2 helms at thhe same time. Helm only drops on hard mode in vog.