The words droop, drupe sound the same but have different meanings and spellings. Why do droop, drupe sound the same even though they are completely different words?
The answer is simple: droop, drupe are homophones of the English language.
To bend or hang downward: "His mouth drooped sadly, pulled down, no doubt, by the plump weight of his jowls” ( Gore Vidal).
To bend or sag gradually: flowers drooping in the midday heat.
To sag in dejection or exhaustion: drooped from lack of sleep.
To let bend or hang down: "He drooped his body over the rail” ( Norman Mailer).
A fleshy fruit, such as a peach, plum, or cherry, usually having a single hard stone that encloses a seed. Also called stone fruit.
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").