is a specific kind of: millet.

is a broader term that covers: old witch grass, old witchgrass, Panicum capillare, tumble grass, witch grass, witchgrass | Panicum virgatum, switch grass | broomcorn millet, hog millet, Panicum miliaceum | goose grass, Panicum Texanum, Texas millet.

is a member of: genus Panicum, Panicum.