A homophonic pun creates humor by play on words that sound the same but have different meanings, such as "I'm reading a book on anti-gravity. It's impossible to put down." A homographic pun, on the other hand, plays on words that are spelled the same but have different meanings, like "I used to be a baker, but I couldn't make enough dough." Both types of puns rely on wordplay to create humor, but one focuses on sound while the other focuses on spelling.
