Differences between sequence diagram and collaboration diagram

Extend is used when a use case adds steps to another first-class use case.

For example, imagine "Withdraw Cash" is a use case of an Automated Teller Machine (ATM). "Assess Fee" would extend Withdraw Cash and describe the conditional "extension point" that is instantiated when the ATM user doesn't bank at the ATM's owning institution. Notice that the basic "Withdraw Cash" use case stands on its own, without the extension.

Include is used to extract use case fragments that are duplicated in multiple use cases. The included use case cannot stand alone and the original use case is not complete without the included one. This should be used sparingly and only in cases where the duplication is significant and exists by design (rather than by coincidence).

For example, the flow of events that occurs at the beginning of every ATM use case (when the user puts in their ATM card, enters their PIN, and is shown the main menu) would be a good candidate for an include.

Here's some explanations from the Visual Studio 2015 docs:

UML Class Diagrams: Reference: https://docs.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2015/modeling/uml-class-diagrams-reference

5: Association: A relationship between the members of two classifiers.

5a: Aggregation: An association representing a shared ownership relationship. The Aggregation property of the owner role is set to Shared.

5b: Composition: An association representing a whole-part relationship. The Aggregation property of the owner role is set to Composite.

9: Generalization: The specific classifier inherits part of its definition from the general classifier. The general classifier is at the arrow end of the connector. Attributes, associations, and operations are inherited by the specific classifier. Use the Inheritance tool to create a generalization between two classifiers.

13: Import: A relationship between packages, indicating that one package includes all the definitions of another.

14: Dependency: The definition or implementation of the dependent classifier might change if the classifier at the arrowhead end is changed.

15: Realization: The class implements the operations and attributes defined by the interface. Use the Inheritance tool to create a realization between a class and an interface.

16: Realization: An alternative presentation of the same relationship. The label on the lollipop symbol identifies the interface.

UML Class Diagrams: Guidelines: http://msdn.microsoft.com/library/dd409416%28VS.140%29.aspx

Properties of an Association

Aggregation: This appears as a diamond shape at one end of the connector. You can use it to indicate that instances at the aggregating role own or contain instances of the other.

Is Navigable: If true for only one role, an arrow appears in the navigable direction. You can use this to indicate navigability of links and database relations in the software.

Generalization: Generalization means that the specializing or derived type inherits attributes, operations, and associations of the general or base type. The general type appears at the arrowhead end of the relationship.

Realization: Realization means that a class implements the attributes and operations specified by the interface. The interface is at the arrow end of the connector.

Let me know if you have more questions.