spritesheet - What is the difference between a sprite sheet and a texture atlas?

I wondering what the difference is between a sprite sheet and a texture atlas?

Aren't both the same? In a sprite sheet you have some Sprites and in a texture atlas you also have some sprites, so what's the difference?

Answer

A sprites-sheet (often refers to a large image that) is supposed to contain the animation frames of a specific 2d character or projectile in a game. You can almost think of it as the model of a 2d-character. It stores all the various animations created for a specific character.

A texture-atlas (is often taken to mean a large 2d image that) contains many textures. You can think of these as 2d images "painted" over 3d objects or otherwise applied to them as part of a shader to explain to the renderer (the part that converts 3d data into a 2d image) how they reflect light (normal map) or if there are any grooves, bumps or cracks on their surface (bump map) or possibly something else altogether like opacity and what not. This term (texture atlas) will often be used in a 3d game environment. Any 3d object (e.g a weapon, a garbage can) or character can have a texture applied to it. Especially 3d levels may require multiple different textures for various walls and elements in the 3d scenery. All these textures can be contained accessibly and effectively in a single large image composed of many squares (subregions) devoted to a specific model.

Also, it may be important to note a texture atlas often contains character skins (character textures) and that the actual animation is (stating the obvious) not stored as 2d imagery as the animation in such cases is generally based on deformation of the mesh with tools like bones.