The words pixie, pyxie sound the same but have different meanings and spellings. Why do pixie, pyxie sound the same even though they are completely different words?
The answer is simple: pixie, pyxie are homophones of the English language.
A fairylike or elfin creature, especially one that is mischievous; a playful sprite.
A creeping evergreen shrub (Pyxidanthera barbulata) having small white or pinkish flowers, native to pine barrens of the eastern United States.
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.