The words popery, potpourri sound the same but have different meanings and spellings. Why do popery, potpourri sound the same even though they are completely different words?
The answer is simple: popery, potpourri are homophones of the English language.
Offensive The doctrines, practices, and rituals of the Roman Catholic Church.
A combination of incongruous things: "In the minds of many, the real and imagined causes for Russia's defeats quickly mingled into a potpourri of terrible fears” ( W. Bruce Lincoln).
A miscellaneous anthology or collection: a potpourri of short stories and humorous verse.
A mixture of dried flower petals and spices used to scent the air.
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").