Previs vs Postvis
Previs artists are responsible for creating a rough idea of what the shot is going to look like for the directors to review. The benefit of using previs is so that the team has an idea of what the shot will look like before spending the money to go ahead and film (or pay a team to go ahead and start working). Oftentimes the animation does not have to look good- what’s important is that the camera work, placement, and timing can be reviewed.
Postvis artists apply the finishing touches after filming. This can include visual effects and additional animation to show the director as a blueprint for what the final version will look like. This postvis work will then be brought to the final animation team to create.
Techvis is a subset of these that involves taking the previs or postvis work and making it precisely accurate to the millimeter in order to make sure that it reflects what the equipment that will be used is capable of.
VFX vs Film vs Game Animation
VFX Animation is most often used in conjuction with live action film and involves adding in particle and light effects, rotomation- animating on top of shots using a motion track- or animating in CGI objects, like weapons and superhero suits.
Film Animation usually refers to a movie that is entirely 3D Animated and may be more similar to a Pixar project, with a cartoonish and less realistic style.
Game Animation is usually a longer project. It’s less stylized, and requires the team to take into account the player’s control and world exploration. Everything must be seen from any and all angles.