While making video animations, animators go for many phases like sketch animation, stop motion animation and computer animation. Animators go for 2d and 3d techniques to make out final end result.
2D animation: It is like traditional animation that existed many years before. Either created by hand or computer and required one image followed by another in slightly different position , and followed by yet another image by different position and so on and on. Earlier they were created by hand. But later on with help of computers, image creation and manipulation can be easily worked out. They have flat images movement and they are represented in height and weight dimensions. In earlier times, artist drew sketches with help of pencils where every frame get transferred in full colour onto cells .Each cell was throughout drawn and painted and then photograph against background image in order to create films frames. Nowadays animation is created through 2d animation software. Even if they are handmade, still often colourised and transferred to the cells using computers.
3D Animation is totally different from 2d both in process and end results. They produce more realistic images and are represented in three dimensions like height, weight and depth. Main features of 3d animations is that they create more realistic textures and lifelike images and once created 3d animation can be treated much like a physical object or an actor. In 3d animation lighting source and camera angle can be changed but in 2d all this is possible only difficult to change a scene during editing process. And in 2D and stop motion you can settle for a drawing every 3-5 frames or even not have it move at all for a few seconds, in 3D we always have to keep the character moving.