On the official sit where you have to choose a cpu to download the wallet there are many models missing.
In fact, all those earlier intel core i5/i7 like sandy bridge that support avx but not avx2
As a result, that wallet version is never recommended for download and users are force to choose standard instead
The standard version is for non-avx2 CPU's.
If you select any of the CPU's in the list, the AVX2 version is shown.
This is correct.
(Go and try running the AVX2 version on a non-AVX2 CPU, report back your findings)