The words rathe, wraith sound the same but have different meanings and spellings. Why do rathe, wraith sound the same even though they are completely different words?
The answer is simple: rathe, wraith are homophones of the English language.
Archaic Appearing or ripening early in the year, as flowers or fruit.
The ghost of a dead person.
An apparition of a living person that appears as a portent just before that person's death.
Something shadowy and insubstantial.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").