The words toady, tody sound the same but have different meanings and spellings. Why do toady, tody sound the same even though they are completely different words?
The answer is simple: toady, tody are homophones of the English language.
A person who flatters or defers to others for self-serving reasons; a sycophant.
To be a toady to or behave like a toady. See Synonyms at fawn1.
Any of various small birds of the family Todidae, of the West Indies, related to the kingfisher and the motmot and having colorful, predominantly green plumage and a bright red throat.
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").