Papua New Guinea is the only country that is in Papua New Guinea. It is officially called the Independent State of Papua New Guinea. However, it occupies the eastern half of the island of New Guinea. The western half is occupied by West Papua, an Indonesian province.
There is no western part of Papua New Guinea which is not already known an Papua New Guinea. Papua New Guinea occupies the eastern half of the island of New Guinea, and the western half is occupied by the Indonesian province of West Papua, which was previously known as Irian Jaya.