differance between ER Diagram and Entiy Assication Diagram

differance between ER Diagram and Entiy Assication Diagram

I am trying to create a conceptual data model using PowerDesigner, I found
a conflie between two methods:
Create two entities and relations between them
Create an association and three entities and two relationships.
knowing that both methods give the same result on the generation of
physical data model
both methods are illustrated by the following picture