What is the difference between 2D and 3D graphics?

2D can be viewed from1 angle,3D can be viewed for infinite angles.

2D or2 dimension is viewed as a drawing on paper or a cartoon on screen. It may be said that a cartoon is called2d due to the fact it has2 dimensions: The moving character and the stationary background. 

3D or3 dimension is observed in everyday life and in computer generated graphics. The entire sides of the image can be observed. in2d you can only see a flat surface. In3D you can observe an entire object in different angles, such things is possible through the use of computer generated graphics.

"2D graphics" is exactly as it sounds... graphics that only deal in a2 dimensional space. 3D graphics use a3d coordinate system and vector graphics to plot/draw things. Because things are in a3d space, objects can be in front of other objects. Objects can be displayed from a perspective viewpoint in which the further an object is from the viewpoint, the smaller the object will be. Only after all the calculations for the placement, perspective size/angles, lighting, colors, and textures of the objects are made, is the image is rasterized (turned into a flat2d image that is displayed on the screen.) 3D graphics API's often have many features built in that allow the creation of nice effects such as reflections and light/shading.

The terms "three-dimensional" (3D or3-D) and "two-dimensional" (2D or2-D) are most commonly used in reference to photography and other graphic image technology, such as animation and computer graphics. The difference between3D and2D images is that3D images add the perception of depth. A2D image, on the other hand, has only height and width. The term "three-dimensional" also is sometimes used to describe a physical item such as a sculpture or mobile, which could be described as three-dimensional art, in comparison with a two-dimensional painting.

Three-dimensional imagery cannot be created without duplicating the effect of two eyes working in tandem, which allows three-dimensional perceptive effects such as depth perception. Early3D technology imitated this process with dual-camera or dual-lens setups. Modern computer technology can easily create realistic effects in both3D and2D.

Photography records images for reproduction on flat, two-dimensional surfaces, such as paper prints or display screens. This has the effect of flattening the image, reducing or eliminating the effect of depth. Natural vision produces this effect because the eyes are set slightly apart, allowing the brain to process two different views of the same image. During the late19th century, photographers attempted to rectify this problem with dual still and motion cameras that were designed to work in tandem. Viewing these “stereoscopic” images through special viewers simulated the effect of seeing a three-dimensional image.

2D - Without depth (Z-axis) only shows Length (Y - axis) and Width (X - axis) of the object.

3D - Shows all3 elements i.e, Length Y, Width X and Depth Z 

Dimensions and the techniques:2D if you want to animate anything you want animated frame by frame, but in the3D programs its have a reall time animation it's automaticlly complete the frames between the movement and the other.

If you need more information please read this book " animation survival kit" for richard williams.

3D adds3rd dimension thickness.

2D dael with x & y dimensions

but3D deal with x, y & z dimensions

Depth manipulation.

The difference between2D and3D.2D has Two dimension .3D has Three dimension we have three   side of  any subject..