Fall was first used in England as an alternative word for Autumn, and both terms came over to America. Fall fell out of use in England but both stuck around here
I was gonna say that Fall is more common in the US while Autumn is more common in Britain.
• "Autumn" is derived from the Latin word "autumnus" and entered the English language through French.
•"Fall" is derived from the Old English phrase "fall of the leaf,": reflecting the time when leaves fall from the trees.
•Both terms existed in English for a while, but "fall" became more popular in the American colonies. This may be due to the desire for linguistic independence from Britain.
• By the 19th century, "fall" was considered distinctly American, while "autumn" was favored in Britain.
•The other three seasons, spring, summer, and winter, have single, universally accepted names.