That's kind of like asking how Water Aerobics and Synchronized Swimming are different.
But first, what you think DevOps means? What does being Agile mean? What do they have in common? Once we understand what those two mean to you and what you think they have in common, then we can explore what their differences are.
The best ideas are the crazy ones. If you have a crazy idea and it works, it's really valuable.—Kent Beck