Binnen BPMN zijn er drie manieren om het werk dat binnen een organisatie plaatsvindt ('activiteiten') te modelleren:

1. Proces

2. Subproces

3. Taak

What is BPMN Activity?

A BPMN Activity is simply "Work" that a company or organization performs in a business process. An Activity is can be atomic (Tasks) or decomposable (Sub-Processes).

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BPMN Tasks

A BPMN task is an atomic activity within a process flow. You create a task when the activity cannot be broken down to a finer level of detail. Generally, a person or applications will perform the task when it is executed.

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BPMN Sub-Processes

In BPMN, a sub-process is a compound activity that represents a collection of other tasks and sub-processes. Generally, we create BPMN diagrams to communicate processes with others. To facilitate effective communications, we really do not want to make a business process diagram too complex. By using sub-processes, you can split a complex process into multiple levels, which allows you to focus on a particular area in a single process diagram.

Bron: https://www.visual-paradigm.com/guide/bpmn/bpmn-activity-types-explained/

What are Activities?

The BPMN specification defines an activity as “Work that a company or organization performs using business processes.” An activity can be atomic or compounded, and the types of activity that can be found in a BPMN-based process model are: process, sub-process, and task.

A task is an atomic activity that is included within a process. A task is used when the work in the process cannot be broken down to a finer level of  detail. Usually an end-user, an application, or both will perform the task. A sub-process shares the same shape as a task object, which is a rectangle with rounded corners.

A sub-process is a process that is included within another process. A sub-process can be collapsed or expanded to show or hide its details within the view of the process that it is contained in.

Bron: https://blog.goodelearning.com/subject-areas/bpmn/common-bpmn-modeling-mistakes-activities/

What are activities in BPMN?

An activity is a generic term for ‘work’ that a company performs in a process. Activities are the critical components of BPMN, since business processes are primarily formed by different types of activities. An activity can be either atomic (a task) or non–atomic, compound (a subprocess). Activities are used in both standard processes and choreographies.

Activities have another unique property: it is the only shape that has a performer. That could either be a person or a system. There are just two types of activities: a task and a subprocess. A task is an atomic activity, meaning it has no internal subparts known to the model. A subprocess is compound, or non-atomic, meaning it does have subparts in the model. It can therefore be expressed as a process. Every activity in BPMN is either a task or a subprocess.   

Bron: https://www.inveskills.com/bpmn/bpmn-activity-types-explained/