Tsavorite garnets are the green variety of grossular garnet. Demantoid garnets are also green, and are a variety of andradite garnet. Grossular and andradite have different crystal chemistry. Grossular is calcium-aluminum-silicate, and andradite is calcium-iron-silicate.
Light green colored grossular garnets are sometimes called "Merelani Mint" garnets.
There's more information on garnet in our garnet listing and our garnet buying guide.
Geologist and IGS Team Member