What are the different categories of retail fireworks?

There are ground-based and aerial fireworks. There are several types of ground-based fireworks - roman candles, sparklers, mortars, multi-shot items, fountains, and firecrackers, as well as some specialty items  such as tanks or an aircraft carrier. There are primarily two types of aerial fireworks - stickrockets and missiles with fins or rudders. All of these, when used as directed, can be enjoyed safely.