The words throes, throws sound the same but have different meanings and spellings. Why do throes, throws sound the same even though they are completely different words?
The answer is simple: throes, throws are homophones of the English language.
Plural form of throe.
Plural form of throw.
Third-person singular simple present indicative form of throw.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License 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").