Activity-On-Arc(AOA), Activity-On-Node(AON).

In network planning techniques, such as PERT,CPM,
There are two possible ways of representing
each project: Activity-On-Arc(AOA), Activity-On-Node(AON).

we know that some project management computer packages use both the network representations.

is there real need for using the AoA representation (Because of minimum dummy arc problem)?

If the AoN representation is only used in project scheduling, what is the nature of the mistake made here?

I couldn’t find any clear-cut and admissible explanation.
Thanks to everybody for their contributions.
Mustafa Ege