What is different between a problem class diagram and a solution class diagram

Problem class diagram and solution class diagram are not standard terms in software modeling, but if they are being used, they likely refer to different types of diagrams.

A problem class diagram is a type of diagram that represents the problem domain in terms of classes and their relationships. The purpose of a problem class diagram is to understand the problem space, identify the classes and relationships involved, and form a basis for designing a solution.

A solution class diagram, on the other hand, is a type of diagram that represents the solution domain in terms of classes and their relationships. It is used to visualize the static structure of a system, including the classes and their attributes, and the relationships between them. The solution class diagram is based on the problem class diagram and represents the design of the system.

In other words, a problem class diagram focuses on understanding the problem that the system is trying to solve, while a solution class diagram focuses on the implementation of the solution to that problem.