Font Vs. Typeface
For the longest time, designers have gritted their teeth when someone mis-uses type terminology. The most common case is font versus typeface. The fact is, there are actually different acceptable definitions.
Generally, when we use typeface, we’re referring to the appearance of the the glyphs—their design. When we use font, we’re talking about the file on the computer. So, I design typefaces, but I activate fonts on my computer.
Others also use font for what I call an instance. Garamond Italic is what I call an instance in the Garamond family. Some people call that a font.
I sometimes catch myself misusing the terms. It’s mostly because font is such a short word. Typeface seems a bit laboursome and formal in the spoken word.