Difference between ER diagram and EER diagram

Question

What is the difference between ERD (Entity relationship diagram) and EERD (enhanced entity relationship diagram)?

Answer 1

Entity-Relationship model

You have relationships (image source)

and attributes (image source)

that can also be primary keys (image source)

Enhanced entity–relationship model

You have the same as with the ER model plus

specialisation

partitioning (which are multiple specialisations)

generalisation

aggregation

keys are annotated differently: