Tussah (aka Tassar) is a wild silk. Tussah moths have resisted domestication forever. You have to love that. Tussah is a warm tan colour, and has a bit more texture than Bombyx.
Muga is the Empress of Silk. From the Assam region of India, Muga has a beautiful golden colour that defies description.
Click on an image below to see more information on that yarn.