It is very important to distinguish between the UML model. Different diagrams are used for different type of UML modeling. There are three important type of UML modelings:
Structural modeling captures the static features of a system. They consist of the followings:
Composite structure diagram
Structural model represents the framework for the system and this framework is the place where all other components exist. So the class diagram, component diagram and deployment diagrams are the part of structural modeling. They all represent the elements and the mechanism to assemble them.
But the structural model never describes the dynamic behavior of the system. Class diagram is the most widely used structural diagram.
Behavioral model describes the interaction in the system. It represents the interaction among the structural diagrams. Behavioral modeling shows the dynamic nature of the system. They consist of the following:
Use case diagrams
All the above show the dynamic sequence of flow in a system.
Architectural model represents the overall framework of the system. It contains both structural and behavioral elements of the system. Architectural model can be defined as the blue print of the entire system. Package diagram comes under architectural modeling.