Sequence diagrams, component diagrams, activity diagrams, and collaboration diagrams are different types of UML diagrams that model various aspects of a system.
Sequence diagrams show the interactions between objects over time by modeling message exchanges, while component diagrams illustrate how software components are wired together. Activity diagrams model workflow and process flows, and collaboration diagrams specifically show synchronous message interactions between objects for a use case. Each diagram type serves a different modeling purpose and provides a unique perspective on the system.