A lot of books has mentioned the two different function-Rendering in Layers and Rendering in Passes, but there are still some books or tutorials which confused them, and also because the related name of Maya Render Layer, many people has confused all the concepts.
Here we can see the differences between Rendering in Layers, Rendering in Passes, and Maya Render Layer.
Maya Render Layer:
This is the name of control rendering output function of Maya. As before we would separate layers which have to keep in the archives, at the time a scene is rendering, the layers would proliferate, just like cells, usually one to five or six. If you want to change the camera or act, we have to send the original files to our colleagues for modifying, and separate these layers again. It’s a nightmare for all of us Lighting Artists. However, Maya allow us to gain the same effects just in one scene, and in general, the results are stable.
Rendering in Layers: this is to render individually the different objects which are in one scene. To do this we can adjusted the materials and color convenient in the post production stage.