What is a texture and what is an Image

A developer that starts new in the field of game development of programming with images would have this question and this is a question that is rarely answered correctly and most of the times it is presumed that a texture is the same thing as an image.
The things that I am trying to accomplish here are
1. Difference between Texture and Image
2. Why are textures more memory efficient
3. How a composite texture is better in terms of memory and speed.

There is obviously a difference between texture and image. Texture is the actual data, the raw representation of the picture setup in bytes. An Image is the representation of this texture, say for example the texture is coffee, and the image is like a cup, to have coffee, you need to have a cup to serve it in as you cannot have coffee directly. Textures are used in Cocos2d, Sparrow but not in Objective-C

Another limitation of the mobile OS is that the textures have to be in sizes that are powers of 2. These take up space in memory. So if there is a particular image that you need to display over again, say like a game tile, it is best to create a texture and then the images are created from these textures, thereby saving memory and hassles of the power of 2 dimensions as images can be created from a composite texture.

Using the packing rectangle algorithm, many of the softwares create texture maps or Atlas which are sued by the app to create images from. That way the space usage of the image textures is reduced.

Hope this has been useful.