A data structure diagram (DSD) is a diagram and data model used to describe conceptual data models by providing graphical notations which document entities and their relationships, and the constraints that bind them.
It comprises of several different diagrams representing different aspect of the system, and one of them being a Class Diagram that can be used for data modeling.
Data modeling is the process of creating a diagram that represents your data system and defines the structure, attributes, and relationships of your data entities.