What is the difference between a layer and a component?

My major development framework is the java spring framework. I have to write service layers, controller layer, dao layer, repository layer and so on. There is thousands of tons of layering. I think component based development approach would become more productive than layering. Spring calls every java beans a component. But I think there should be major difference between component and layer. Generally a layer is passive where a component is active. A component fires events, call life cycle callbacks methods and actively handle a task. On the other hand a layer only gives abstraction. So what is the fundamental difference between a layer and a component?