Hi,

There are only 3 true task types - fixed duration, fixed work, fixed units. The task type determines which of the 3 variables change when you change one of the other.

Fixed Duration
You change work - Project changes Units
You change Units - Project changes work

Fixed Work
You change duration - Project changes units
You change units - Project changes work

Fixed Units
You change duration - Project changes work
You change work - Project changes duration.

Effort driven and non-effort driven determine what occurs if you add or subtract named resources. If the task is effort driven and you add or subtract named resources, the total amount of work on the task remains the same. In effort driven fixed units and effort driven fixed work - add more resources and duration decreases. In effort driven fixed duration - add more resource and units decreases.

Non-effort driven tasks - if you add more resources, work increases. Remove resources, work decreases.

I hope this helps.
Julie