Fonts versus Typefaces
They’re not fonts! explains the difference between “font” and “typeface.”
Graphic designers choose typefaces for their projects but use fonts to create the finished art.
Essentially, if you are talking about the appearance of text, you are speaking about what typeface it is set in. “Font” is like an implementation, or an instance of a typeface. Quoth wikipedia:
In typography, a font (also fount) is traditionally defined as a complete character set of a single size of a particular typeface. For example, all characters for 9 point Bulmer is a font, and the 10 point size would be another font.
I’ll have to start saying that correctly.