Granularity of a Process Model 
Process models vary in depth depending on the needs they have to satisfy. Different depths result in process models with different granularity, that is to say, different detail levels. Once again, this granularity depends on the needs the process model should fulfill.
To present a large overview of certain activities enclosed in a process model, a large-grained process model is preferred. It is often used by top-level managers and business analysts who want to have a general overview of the time and resources needed to accomplish the process.
On the other hand, when a detailed model describing not only activities but also different roles and dependencies is needed, then a fine-grained process model is created. It is often used by developers and system architects who need these details to put the model in practice.
Granularity of Process Models in the Process Composer
SAP NetWeaver Business Process Management allows you to create process models with different granularity. With the process composer, you can create a simple outline of a process or a fine-grained model containing all detailed steps. You can model in detail the functions and roles of different participants in the process. To do that, you use lanes, a type of swimlane, specified by BPMN. For more information about lanes, see Defining Roles in the Process Using Lanes.
You can use the subprocess activity type in the process composer to create process models with different granularity. The subprocess represents a more detailed process, referenced by a large process. You can also use subprocesses to split human and automated activities and represent them as a detailed sequence of steps. For more information about subprocesses. see Working with Sub-Processes.