The words pean, peen sound the same but have different meanings and spellings. Why do pean, peen sound the same even though they are completely different words?
The answer is simple: pean, peen are homophones of the English language.
Variant of paean.
The end of a hammerhead opposite the flat striking surface, often wedge-shaped or ball-shaped and used for chipping, indenting, and metalworking.
To hammer, bend, or shape with a peen.
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").