incident, occurrence, event, accident的区别

incident,指事件，小事件
occurrence,
event,指大事件
accident 事故

event / occurrence / incident / happening
All these words describe something that happens.
An event is often something important or interesting: I'll never forget the terrible events of that summer. It can refer to something such as a concert, festival or sports competition:
The tourist guide lists the major events in the town throughout the year.
Occurrence is a formal word and is usually used, with words like common or rare, to talk about how often something happens: Divorce has become a common occurrence in this country.
An incident is often something not very important but that you remember because it is unusual or unpleasant: The movie is based on a real-life incident. It can also refer to a crime or an accident:
The police reported several thefts and one violent incident.
Happening is used to describe something unusual or strange: strange happenings in the town.