"amd64" is the official name, per AMD; just as "ia32" is the official name of x86-32, per Intel. The fact that ia32 (and it's sub-classifiers: i386, i486, etc)

"amd64" is the official name, per AMD; just as "ia32" is the official name of x86-32, per Intel. The fact that ia32 (and it's sub-classifiers: i386, i486, etc) is still somewhat used, while amd64 has almost completely disappeared is 100% due to Intel's marketing shenanigans in the 00s.