What was the difference between Magic and Ultra?

Was Magic the diplomatic codebreaking program while Ultra covered military codes?

Not exactly; Ultra usually refers to Enigma-derived German intelligence, while Magic generally refers to intelligence from Japanese systems, especially diplomatic traffic.

Ultra is most often associated with Enigma-derived intelligence against Germany, including military and some diplomatic traffic. Magic more commonly labels intelligence from Japanese cryptographic systems, especially diplomatic messages, although Japanese military services used additional systems. The categories are historical intelligence labels rather than a simple diplomatic-versus-military division. This distinction helps identify which intercepted material mattered in debates about the Pearl Harbor warning.