In a component diagram, components (component: In component and deployment diagrams, a distributable unit of implementation in a system. For example, a component can represent a physical module of code (source, binary, or executable) or a business document in a human system.) are generic types rather than instances. To show component instances, use a deployment diagram (deployment diagram: An implementation diagram that shows the structure of a run-time system. From it, you can learn about the physical relationships among software and hardware components and the distribution of components to processing nodes.).
Dependencies (dependency: A relationship between two elements that indicates that changes to the target element may cause changes in the source element.) indicate that a client component is dependent upon a supplier component in some way.