Tonight, while having a cup of hot-chocolate, me and my friends had a little discussion about the foam/bubbles/froth formed on the top of the drink.
While I said that it should be referred to as froth, they were referring it to as foam. Now, all my childhood, I was told that foam is used with reference to their origin because of soapy liquids; I can't accept that it should be foam.
My dictionary shows the same meaning for both the words and hence, my question:
Which of the two words, froth and foam is preferable when referring to bubble formation in drinks?