Wow thanks for the enlightenment. I dug into this a bit and found out:
Hyphen (-) — the one on your keyboard. For compound words like “well-known.”
En dash (–) — medium length, for ranges like 2020–2024. Mac: Option + hyphen. Windows: Alt + 0150.
Em dash (—) — the long one, for breaks in thought. Mac: Option + Shift + hyphen. Windows: Alt + 0151.
And now I also understand why having plenty of actual em-dashes (not double hyphens) is an “AI tell”.