ADB has the same physical connection as S-Video. AppleTalk is the protocol, but LocalTalk was the RS-422 implementation, and Apple's first party implmentation

ADB has the same physical connection as S-Video. AppleTalk is the protocol, but LocalTalk was the RS-422 implementation, and Apple's first party implmentation used different cables from ADB. But everyone I know used LocalTalk over "PhoneNet" adapters which used cheap RJ11 phone cable and were way cheaper overall.