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

I would add that ER model is basic model which has all you need for relational algebra as it is (including ISA hierarchy - inharitence nad other stuff I don't remember). And is more abstract (so every box doesn't have to be database table and the other way around some boxes can be more then 1 table)

EER model is closer to what real database look like. So every box is actually table.

I assume the accepted answer is right too, but in my opinion (havent read this anywhere I just think it is this way) EER was created to help people design databases even more then the basic relational algebra. Relational algebra with ER gives u everything you need to model database but you need some compiler which will translate ISA hierarchies and relations into actual tables and with EER your getting what you see. I was using both to design tables - ER is more logical, because it abstracts you from stuff like inheritance since you just tell your ER tool I want this to inherit from that and you dont have to create 2 tables. But EER is better because you see what you get.

Conclusion: ER is basic principle, EER is little bit better tool for actual work with less abstraction.

(My teoretical knowladge of relational algebra is too rusty, so I hope I remember everything right, correct me if I am wrong)