A Super Event is made up of multiple races, but packaged as one. For example, a “MegaPack Challenge” would sign a runner up for the 5K, 10K and Half Marathon. In Race Reports, you would see the runner in the MegaPack report, but also in the 5K, 10K and Half reports (marked that they are a MegaPack runner). The top level reports still work the same – you will see one registration. Bib assignment can be done either with one bib for the MegaPack or a bib gets assigned to each of the individual events (the runner would get 3 bibs).
A Sub Event is useful for starting waves.
Take a look at this quick overview video.