Autumn is more descriptive of the season. It is autumn, autumn weather, etc,
Fall is for the time of the year. School starts in the fall, fall break,
Leaves turn colors in the fall.
Autumn leaves are beautiful.
As clocks go, you can spring ahead, but you can’t autumn back.
You can’t spring back either.
A springbok can spring back.
UK/Rest of Anglosphere: We say Autumn from the French word Autompne and later from the Latin Autumnus.
USA: We say Fall because leaf fall down go boom.
My native speak is finnish and english is just a second language. Brits have complimented me speaking more english than american. And I think it’s because we watched lot’s of BBC produced documents and comedies (Monty Python anyone) when I was young and all the paperbacks I read were english editions.
With that preamble I have to say that I use both. To me autumn is before fall. Autumn is when summer ends, eg. when nights are not warm anymore and you start to prefer the sunny side of the street to the shadow side. Fall on the other hand is much later when the trams start to run late because they are slipping on the fallen leaves on the tracks.
I think i use both. I probably prefer one or the other in certain circumstances, but i couldn’t tell you what determines that.
Okay, I get that. “northward” and “southward” equinoxes sound a bit awkward, but how about “boreal equinox” and “austral equinox” ?
AW-tum, possibly with the “t” de-emphasized to sound a little bit like AW-dum.
Growing up in Philly, fall was the only word I ever heard. I associate autumn with Britain. I think Canadians mostly use fall. FWIW, McGill calls this its fall term (but the second term of the year is called winter, not spring, although it obviously overlaps both).
Couldn’t agree more. (@SanVito was heading that way upthread.)
j
Works for me. I’ll pick fall too. 
Autumn certainly sounds nicer. But here it’s ‘Winter is here’.
Seriously. At altitude it happens very fast. My Wife and I enjoy playing chess on the deck. Had our first snow a few days ago. Deck time is probably 8 months away.
Voted “Fall” as I’m more apt to use that word in everyday conversation than Autumn.
But both work for me, and I have no problem with either.