Yeah, but given the various names others came up for it, it would have been nice to have one short name. It's normal for difference to exist even withing revisions of a chip, so it wouldn't have hurt anyone to use one name, When we say x86, we mean everything Intel from the 1980s until now, including Cyrix, AMD, Via, etc. 32bit or 64bit.
The AMD64 usage implies non-compatibility with EM64T..