[Lanthanide]

From wiki:

"Both acetaminophen and paracetamol come from a chemical name for the compound: para-acetylaminophenol and para-acetylaminophenol."

The former is the name used by the United States Adopted Name (USAN) while the latter is the (International Nonproprietary Name (INN) one.

[ac29]

Same for Tylenol (most common branded version of the drug, at least in the US): para-acetylaminophenol

[saghm]

Ah, that explains why I've only heard the name acetaminophen (I'm an American)