In Kickshaws in the February 1998 Word Ways, Richard Lederer does well to raise the problem of describing the relationship between a pair of words in respect of meaning, appearance (spelling) and pronunciation. The last is always likely to cause problems: for example, wen and when are pronounced the same by most people, but not by those who most of my dictionaries). Shades of meaning may also cause disagreements. Derivation may also be of interest, though not always known.
"Homos and Heteros: The Truth Revealed,"
Word Ways: Vol. 31
, Article 23.
Available at: http://digitalcommons.butler.edu/wordways/vol31/iss3/23