These are the most important events of the racing season. There should only be one to three of these events because training will be designed to peak for these events. (A races)
These are events that you want to do well in, but are not the main focus of your season. We may rest for the event for a short time, but usually they will be approached as race pace training to sharpen your race skill set.
These events are of the least importance. They are done for fun and a good workout!