IEC 646 is the name of a set of ISO standards, it has a 7-bit character code and the first edition came out in 1967.
ISO/IEC 646 is the name of a set of ISO standards, described as Information technology  ISO 7-bit coded character set for information interchange and developed in cooperation with ASCII at least since 1964. Since its first edition in 1967 it has specified a 7-bit character code from which several national standards are derived. 
