What is the difference between a delegate and an event in .NET Core?

In .NET Core, a delegate is a type that defines a method signature and can refer to one or more methods with matching signatures. Delegates are used for defining callbacks or for passing methods as arguments to other methods.

On the other hand, an event is a mechanism that allows an object to notify other objects when something interesting happens. It is based on delegates and uses them to reference methods that should be called when the event is raised.

The main difference between delegates and events is that delegates are used to define the signature of the method, while events provide a higher-level abstraction of the concept of a notification or a change in state. 

Events can only be raised by the class that declares them, while delegates can be invoked by any code that has a reference to them. 

Additionally, events can have multiple subscribers, while delegates can only have one.