Here's why:
* Homophones are words that sound the same but have different spellings and meanings.
* Homonyms are words that have the same spelling and pronunciation but have different meanings.
Examples of how "rock" can be used as a homophone:
* Rock (noun): A solid piece of stone.
* Rock (verb): To move back and forth rhythmically.
While "rock" can refer to different things (a piece of stone vs. a musical genre), the spelling and pronunciation are the same.