There are a few key differences between a Photoshop composite image and a layered image. First, the image is only one color, whereas the entire image is created using multiple colors. The second difference is that the blended layer is not viewed as part of the original image but rather as part of a Photoshop layer. The layer is a type of template, which can be used to create an image or layers if you prefer.
The best way to create composites is to use an appropriate software program. If you’re not familiar with digital imaging, you may want to work with a software package that creates composites for you. It may also be helpful to use a tutorial that shows you how to use the appropriate software. There are many free tutorials available online, so before you spend any money on composite-making programs, it’s a good idea to investigate what Photoshop offers.