What's the difference between activity and event
Each of those words have several meanings, most of which are not really related to each other. However, there is a common meaning for at least one sense of each of those words around the concept of "occurrence" -- something that happens.
In the case of "event", it can mean very generally anything that happens, but often it means a social gathering, something that happens with people at a specific time or place.
In the case of "activity" it can mean something that does some process, usually implying an active process driven by some impetus. It can also mean a planned event where people are active participants, often a hands-on educational event.
Examples:
Many people attended the social event because it was well promoted.
Our digestive systems carry on their activities usually without our notice.
The children made clay figures during the art activity.
As I said, there are also many other meanings for each of those words which don't fit any of the definitions above.
If you want to join in the National Ranch Day, you join in an event or an activity?
@Acer
Its both, but I'd call that one an event.