The words toe, tow sound the same but have different meanings and spellings. Why do toe, tow sound the same even though they are completely different words?
The answer is simple: toe, tow are homophones of the English language.
One of the digits of a vertebrate.
The forepart of a foot or hoof.
The terminal segment of an invertebrate's limb.
The part of a sock, shoe, or boot that covers the digits of the foot.
Something, such as a tugboat, that tows.
To draw or pull behind by a chain or line: a tugboat towing a barge. See Synonyms at pull.
The act or an instance of towing.
The condition of being towed: a car with a trailer in tow.
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").