A graphic designer has nothing to do with 3D modelling, except perhaps with primitives that need to be included, but nothing more. They are not responsible for modelling the visually accurate meshes included in a game, and typically work in functions of marketing.
Actually "graphic design" is broad and totally meaningless term saying that you are qualified for (one of) the artistic department(s), but nothing more. It's kind of my job.
Then you have "real" professional terms commonly used :
- Artistic Director : elaborates concepts from scratch, early art, and decides of tha artistic direction. Is usually above the artistic departement as he then hands his concepts to the team, for them to get actually produced.
Then the other artists :
- Animators, 3D modelers, 3D texturers, 3D special effects and particules specialists, painters/illustrators, 3D level design specialists, graphic engine specialists, storyboarders, web designers, interface & 2D designers, advertisement and communication specialists, etc, depending on the size of the company.