The words rex, wrecks sound the same but have different meanings and spellings. Why do rex, wrecks sound the same even though they are completely different words?
The answer is simple: rex, wrecks are homophones of the English language.
An animal which has a genetic recessive variation that causes the guard hairs to be very short or fully lacking.
Plural form of wreck.
Third-person singular simple present indicative form of wreck.
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").