The difference between gammon and ham, which both refer to meat from the hind legs of a pig, is that gammon is sold raw, while ham is sold cooked or dry cured and is ready for consumption. Once gammon is cooked, it is called ham.
Gammon is cured just like bacon. Ham is cooked and served fresh or dry cured using honey, sugar or maple syrup. Ham is often served during holidays such as Christmas and New Year's Eve. Leftovers can be sliced up to make sandwiches. Gammon can be purchased with or without the bone, smoked or unsmoked. Before traditionally cured gammon is cooked, it has to be soaked in cold water to remove excess salt.