All Americans are apparently not created equal

Yesterday mid-afternoon I stepped into a cafe with a friend.  Good day–an espresso and an Americano, if it pleases you, I requested.  (If it’s in italics, it happened in French.)  My intent was to get my friend a café americano, or an espresso with hot water added–it’s something like American brewed coffee.  Careful, the waiter said–an américain [American] is a cocktail.  If you want an “Americano,” you have to ask for a café americano.  He explained to me that an américain is a sort of very dry martini with Campari.  Lesson learnt!

• le café Americano: espresso with hot water added.  I’m not sure what the difference is between this and a café (r)allongé.
• un américain: a type of cocktail.  No French Wikipedia entry for this, so no picture.