The text below was found on Harmony Central from a post were someone asked the same question 15 years ago. I don’t know if it’s the correct explanation or not but at least it’s an answer to your question-
Tube Store options
Standard Test = normal test to make sure tube is operational
High Gain = actually opposite of what it sounds, handles more high gain therefore making it actually have LESS gain
Matching = should be self explanatory, matches tubes to be same
Balanced Triodes = what you normally use for phase inverter slot
Matched + Balanced Triodes = same only matched, probably won't use for guitar head
Low Noise and Microphonics = mainly for playback equipment