The words pall, pawl sound the same but have different meanings and spellings. Why do pall, pawl sound the same even though they are completely different words?
The answer is simple: pall, pawl are homophones of the English language.
A cover for a coffin, bier, or tomb, often made of black, purple, or white velvet.
A coffin, especially one being carried to a grave or tomb.
A covering that darkens or obscures: a pall of smoke over the city.
A gloomy effect or atmosphere: "A pall of depressed indifference hung over Petrograd during February and March 1916” ( W. Bruce Lincoln).
A hinged or pivoted device adapted to fit into a notch of a ratchet wheel to impart forward motion or prevent backward motion.
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.