Swimlanes are one of the five basic categories of BPMN elements and act as a container for partitioning a set of activities from other activities. BPMN 2.0 defines two different types of Swimlanes: Pools and Lanes.
A Pool represents a Participant in a business collaboration. In a BPMN diagram, a Participant can be a specific Partner Entity like a company, or a Partner Role such as a buyer, seller, or manufacturer.
A Pool acts as a container for a full business process.
And the process has to be fully contained within the Pool. The sequence flow cannot cross outside the boundaries.
A Pool has two basic representations – “white-box” and “black-box”. White-box representation shows the internal details of the Pool, whereas a black-box representation hides any processes.
Black-box representation is best used when the Pool doesn’t reference a process but only an external process participant. Therefore, black-box pools are commonly named according to the process participant they represent, whereas white-box pools are commonly named according to the contained process.
A Lane is a sub-partition within a Pool and extends the entire length of the Pool, either or horizontally or vertically.
Lanes are used to organize and categorize Activities within a Pool. In practice, Lanes are commonly used for allocating activities to roles, systems or the organization’s departments
In addition, Lanes can be nested or defined in a matrix. For example, in a Pool, there could be an outer set of Lanes for company departments and then an inner set of Lanes for roles within a department.
Although BPMN specification explicitly describes the possibility of “matrix” Lanes, they are rarely used as well uncommon in BPMN modelling tools. Nevertheless the matrix structure of Lanes might provide optimal organization of process activities.
At a glance, both swimlane elements look very similar. However, they have completely different meanings. A Pool represents a participant in a business collaboration and may act as a container for a single process, whereas a Lane represents an “activity-classifying mechanism”.Business Process Analysis BPMN Video