Question for ya, Bingley. Given the roots of the three terms you share (homo, phone, graph, and nym), I wonder if a homophone must have different spelling and if a homograph must have a different spelling.

If homophone means "same sound," then words that sound identical are homophones regardless of whether the spellings are identical or not. Similarly, words that are spelled the same regardless of whether the pronunciations are different are homographs.

Am I being too inclusive?