It’s hard to describe the difference on a training course, and you don’t often get to see a network diagram drawn in both ways, but HERE IS ONE!
Which one do you prefer?
1 – PERT aka activity on arrow
2 – CPM, aka Activity on Node
For me, CPM wins hands down, so that’s why I teach it. No need for dummy activities (the dotted lines on the top diagram). It works so well with Post-It notes too!