Yes. Mutton is the meat of the adult sheep, lamb is the meat of a juvenile sheep. The flavor is different, but in a volume-ish way. If you think of the flavor of lamb as being a 4, the strength of the mutton flavor is like a 7-8. It's the same flavor, there's just way more of it.
Mutton is really goat. Lamb is just lamb meat. IMO, lamb is sometimes harder to cook because of the smell - you need the right spices to get rid of the smell. Easy to get mutton in most urban areas in the west - just look for a Halal meat shop.
