Difference between associative entity and associative relationship attribute?

Question

What is the difference between an associative entity and an associative relationship attribute? In my book titled, Modern Database Management (Hoffer, 11th edition), the aut

Answer 1

In ER diagramming, M:N relationships can have associative entities OR single associative attributes that describe the relationship. The difference is, associative entities must have a unique identifier and associative attributes don't. According to the book, an associative entity must have:

1-all the relationships for the participating entity types are M:N relationships 

2-the resulting associative entity type has independent meaning to the end user and has an identifier 

3- the entity has one or more attributes 

4-the entity participates in 1 or more relationships independent of the entities related in the associated relationship.