When following Alistair Cockburn's model on different levels of use cases, the highest benefit lies in the user-goal and sub-function levels. In this comparison we consider user-goal level use cases to be regular use cases, as this is most likely the level you will encounter in a RUP or a waterfall styled project. Use cases that are considered as smart use cases comprise both the user-goal and the sub-function level.
In comparison we see the following aspects:
| Aspect | Regular use cases | Smart use cases |
|---|
| Intention | Describe a single user goal | Model a single user goal |
| Visual appearance | If a diagram is used, it most likely contains a number of actors and a single use case ellipse. In most cases no diagram is modeled. | Smart use cases heavily use the visual representation. A smart use case diagram will contain a number of actors, the user-goal level use case, and any number of surrounding sub-function level use cases |
| Textual appearance | A user-goal level use case is desribed in a document. This document will contain features such as pre- and post-conditions, the basic flow (happy days scenario) and any number of alternative flows. As user-goal level use cases can be quite large, it is no exception that there are many (up to hundreds) of alternative flows. Use case documents will often features screen design for all screens involved, and all navigation between these screens. Sometimes such use case documents have over 50 pages of documentation. Additionally, a use case realization document may contain any additional properties required to translate the use case to code. | Each smart use case can be described in a test document as well, containing similar features as regular use cases. However as smart use cases are much smaller (also the user goal level smart use cases), the basic flow is short, and the number of alternative flows is very limited, if present at all. Moreover, as smart use cases tend to be stereotyped, the use case description can be even more minimal. |