I'm unsure why we even need the "nano", "pico" and other classifications. A 40gal is 40 gallons regardless of if it's considered a nano, a small tank, a big tank or whatever.
Why must we name EVERYTHING in this hobby? From corals that are so slightly different in pattern to the point where people are arguing over what it is based on how many spots it has near the mouth to whether or not a tank should fall into a certain classification based on size.
If we treated people the same way we'd be horrible people. Judging how good or bad someone is based on size or skin colour.
Next thing you know people will be arguing over what to name certain light settings. "No it's dusk because the blues are 60% brighter than the whites."
"No, it's late dusk because the whites are below 10%".
Geeeeez! Just accept things for what they are and stop trying to push everything into some sort of category. Things can't be left alone in this hobby. Everything needs to be something....