• model - is representation-agnostic
• diagram - is a representation of a model

the same model can be represented by many different diagrams

Model Types

• Entity Relation Model (ERM) - used for describing entities and their relationships (ERD)
• Software System Model - used to describe a software system (C4 Model)

Diagram Types

• Business Process Modeling Notation (BPMN)
• C4 Model (Context - Components - Containers - Code)
• Entity-Relationship Model (ERM) - Entity-Relationship Diagram (ERD)
• Unified Modeling Language (UML) Diagram