When you enter into the world of graphic design on a professional level, you are expected to know certain things that the layman does not. For example, you should be aware that a font and a typeface are two different things. You should know the proper way to space lettering on a poster. You should have a good grasp of image placement for the most effective genre of poster…and that is only the beginning.
The subtleties in this line of work as extreme, because you are touching on so many different sources. Graphic design is artistic, creative, technical, technological and precise. Which is why when someone gets confused by something like the difference between logos and icons, it is understandable. The two are very similar, so it can be difficult to ascertain the little deviations that make each unique.