PERT diagram for software engineering (AOA and AON)

Two categories

There are two types of PERT diagrams: AOA and AON.
Arrow Activities (AoA) and Node Activities (AoN) are both a type of Program Evaluation and Review Technique (PERT), a well-known method used in completing projects. Analyze various tasks, especially when it comes to the time required to complete each task and the minimum time required to complete the entire project.
Traditionally, activity sequence diagrams utilize boxes or even rectangles to display activities, which are called nodes. These nodes are connected to other nodes by using arrows; this will indicate the existence of dependencies between the connected activities.
Project networks typically show the relationships that exist between tasks in a project. Illustrating these activities by using arrows between nodes or even event nodes is the primary way to draw these relationships.
For AoA diagrams, showing the relationship between finish and start is a limited thing. This means that the arrow represents the span of time from the event that the arrow begins to the event that it ends. Activities represented by arrows must be added to illustrate some of the more complex relationships and dependencies that exist between activities.

However, when it comes to AoN graphs, activities are placed on nodes. Interconnecting arrows illustrate the dependencies that exist between activities. They are more flexible and can account for the main types of relationships. Since the activity is on the node, you can usually put the data on the activity.

Also, since activities are placed on nodes of the AON diagram, the arrows can move in any direction and therefore represent a wide range of dependencies (start to end, start to start, end to start, end to end) .

AON is generally used to describe it, but in actual applications there are still choices, and it depends on your own project. For better choice, the basic differences between AOA and AON are as follows:

1. A significant disadvantage of AoA networks is that there are multiple different possible networks describing the same project. In contrast, Activity on Node (AoN) representation is unique.
2. Having both AoA and AoN networks for a project is an advantage because some plans and optimization techniques strictly require the use of the AoA format, while others require the use of the AoN format.
3. AoN diagrams are generally easier to create than AoA diagrams.
4. For inexperienced users, AoN diagrams are easier to understand than AoA diagrams.
5. If there are changes, it's easier to make them on an AoN chart than on an AoA chart.
6. The AoN network focuses on tasks, while AoA focuses on events.

Reference link: PERT Templates (AoA and AoN) on Creately