“the physical embodiment of a collection of letters, numbers, symbols, etc. (whether it’s a case of metal pieces or a computer file) is a font. When referring to the design of the collection (the way it looks) you call it a typeface.”
“When you talk about how much you like a tune, you don’t say: “That’s a great MP3”; you say: “That’s a great song”. An MP3 is the delivery mechanism, not the creative work, just as a font is the delivery mechanism, and a typeface is the creative work.”