Some Pre-Production work.
There are many types of companies one is a Development Studio which is basically a Studio committed to making video games and releasing them to the public this is also known as a Games Development Studio some examples are; Bethesda Softworks, Gearbox Software, Neversoft and Pandemix Studios.
These are some of the most famous Games Studios that are around right now, within these Game Studios there are different Departments, some of these may include;
A 3D modeller models anything from characters to furniture to scenery and just about anything else to do with the game, they can have specific modellers for certain things like a character modeller or level modeller.
A Programmer programs everything in the game, such as when events are meant to happen, what things do, how the character acts and behaves and everything else you can imagine, again the programmer can have certain tasks as there can be many programmers on a team.
Level designer design the game levels that are in games quite easily put but they have to avoid a lot of bugs and issues in the games and then if there are still bugs the Q&A testers will find them and surely annoy the game designer/s, again as for the other there can be more than one working on a game