In reply to ranju.ranjitha555@gmail.com:
Modules and classes are both containers for declarations.
Modules instances get created at compile/elaboration. The declarations in a module have static lifetimes, meaning they exist from before time 0 until the simulation ends. They cannot be created or destroyed during simulation.
Class instances only get created during simulation. The declarations inside a class have dynamic lifetimes, meaning they get created or destroyed by executing procedural code.
Please see
https://verificationacademy.com/forums/systemverilog/when-should-be-program-block-dynamic-or-static-members-static-program-block-members-automatic-program-blocks#reply-38825
https://verificationacademy.com/forums/systemverilog/what-exact-difference-between-static-tasks/functions-and-automatic-tasks/functions-please-explain-clear-example#reply-44935