Graphic design

Multimedia - It is simple the use of a variety of artistic or communicative media. This includes text, graphic, audio, video etc.
Animation - Making imaginary character or a product and putting life in it. This word Animation is basically made from Greek or Latin words ani (means object or thing) and motion (means movement), in short making objects and things into motion. It 2D Animation, 3D Animation and VFX (Visual Effects).
Graphic Design - Graphic Design is the foundation of every kind of design. It's the father of all. It includes Print Design, Graphic, Web everything. A graphic designer can be a web designer, a graphic designer can become an UX designer or Print Designer as well. But to be exact graphic design is simple designing graphics. Say it designing a movie character, icons, cartoons, textures, backgrounds, logos, business cards, flyers, brochures and many more.
Web Design - This includes designing web sites and web sites only as the name suggest. In which its totally up to designer which fonts to use in a web site, which color, what is the style, what could be the effects. A Web Designer thinks of user aspects, prototyping etc. and then a front end developer puts his/her web design to motion.
VFX (Visual Effects) - Visual Effects (abbreviated VFX) are the processes by which imagery is created and/or manipulated outside the context of a live action shot. Like you've seen Spiderman, Superman etc in movies and comics they were not real but after watching films we take it as real. So how come they got such powers and all that its basically visual effects. In VFX we animate live things or you can say live characters. We put live things to motion. Movies like Jurassic park, superman, Spiderman all comes in this category.
Gaming - It belongs to Game Development Industry. It includes motion gaming. Every type of game design comes in this category. Say Need For Speed, Counter Strike, Resident Evil, Batman, Vice City, Prince of Persia, Angry Birds. It includes game programming as well as design or development in simple words.

You may select any stream of your choice.
You will generally require a qualification to be an art director. Many are graduates of art, architecture, theatre, interior or 3D design courses. You could also undertake higher-level courses in film and/or theatre production design. After training, it will be vital for you to acquire on-the-job experience of how art departments work, studio practice, working on locations, etc.
What is the best route?
To become an art director, you need to learn your skills on the job. This involves starting out as an Art Department Assistant and progressing through the grades, e.g. to junior draughtsman, then to draughtsman or assistant art director. Although, this progression will take a number of years, it is a crucial process during which you will gain the knowledge and experience you require to become a good art director.
If you study film, television and theatre design you could also gain experience working on low budget productions before progressing to junior roles on television programs or feature films.
You could transfer across from a similar role in the theatre, having learnt to conceptualize ideas and communicate them dramatically and visually. However, you will have to learn techniques specific to film and TV.