Q: what's the difference between A6 and A13?
A: A13 has G in it. it's just a weird quirk of society, that A13 means A7 with 13, and A7 is short for A dominant 7, which means it has b7 in it. A6 is not a dominant 7 chord. and don't ask me what dominant means, it just means it includes b7. it is not dominating anything in any way. except actually it probably dominated the blues scene so hard that it was the only chord anyone ever used so they stopped saying dominant and A7 became the default shorthand for A dominant 7