What's the difference between entity and class?

Question

Is entity an instance of class?

Answer 1

I copy from this paper, "Entity based Programming Paradigm", Nimit Singhania. University of Pennsylvania:

An entity is an abstract unit that represents a group of nodes or sub-entities. It uses the services provided by its sub-entities and collaboration between these sub-entities to achieve its required goals. It has its own identity and appears as a single unit to the external world just as in real life a team or an organization is a whole unit and not just a collection of individuals. A distributed system is essentially a hierarchy of entities where each entity has a specific role and provides specific services [...]

[...]The entity abstraction is very similar to an object in object oriented programming. The key difference between an object and an entity is that an entity is an active and a live unit while an object is passive. An entity consists of live subentities interacting with each other to provide a service and can possibly interact with the other entities. Whereas, an object consists of only static fields and properties that can be queried and manipulated by the external world. But, many insights from object oriented programming can be carried over to this programming paradigm. We can have classes and types of entities, where a class might provide specific services and functionality to the rest of the system. Also, we could define abstract entities which implement the core structure and some basic protocols for interaction between nodes and these could be extended further to realize the actual entities. Similarly, we could define interfaces that define a set of services. These interfaces could be implemented by multiple entities with different guarantees and based on the requirements, one of them could be chosen by the programmer to provide the required service.