Entity Relational model is an example for Conceptual Data MOdel Physical Data Model Representational Model

Example: What is a Conceptual Data Model?

# What is conceptual data model to me?

There are many good definition of this term. 
In layman's term, it's the big picture of a Business's data 
domain and processes that occur in it. During the design 
phase of an application or a database, a team creates conceptual, 
logical and physical data model. Some teams combine conceptual 
and logical data model effort while others do only the 
physical data model. Here is a basic example of the 
conceptual data model. 

+-------------+                +-------------+
| Customers   |--------------> |   Address   |
+-------------+                +-------------+
      |
      |
     \|/
+-------------+                +-------------+
|   Orders    |<-------------- |   Products  |
+-------------+                +-------------+