The words eyelet, islet sound the same but have different meanings and spellings. Why do eyelet, islet sound the same even though they are completely different words?
The answer is simple: eyelet, islet are homophones of the English language.
A small hole or perforation, usually rimmed with metal, cord, fabric, or leather, used for fastening with a cord or hook.
A metal ring designed to reinforce such a hole; a grommet.
A small hole edged with embroidered stitches as part of a design.
A very small island: rocky islets off the coast.
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.