Pop-up Description of a section

I do not know if this is by accident or on purpose, but only some of the sections have a pop-up describing the section. For example:
Hover over Call of Duty Series and there is a description:

Hover over Graphics and no description:

While I know that graphics is pretty self-explanatory (at least for me), just something I have noticed in case someone gets confused on what a section entails for whatever reason!