Cranky is a more wide ranged term , it means strange(in a bad way) and the one who always stays angry and irritated no matter what. So it's a long time term . He is a cranky person. Whereas grumpy is used when one is angry or irritated because of something that happened in specific . Like He was grumpy today because he failed the test. I hope you understood it. If didn't ask me the queries again. I would be more than happy to help you with it. And don't have a good day..have a great day . 😊

Cranky means bad-tempered and irritable. For example: he was cranky after doing 8 hours of work. Grumpy means being easily annoyed and testy

I use them interchangeably.