Business events
Events that have business value and that express something that happened in a business process, e.g. ContractSigned. These events contain data that is known by business.

‍State transfer events
Events that hold the latest state for a data entity. These events don’t tell you what has happened or changed, they hold the latest state which is useful for aggregation of data or creating views / data caching.  

Raw machine events
Often IOT events. Raw events, hard to read.

‍Internal events
Events that are only used in 1 microservice. They don’t hold important business data that should be produced as a business event.