Python dataclasses (introduced in PEP 557) are excellent for reducing boilerplate in classes that primarily exist to store data. However, they are essentially "dumb" containers without validation or advanced serialization functionality built in.

Pydantic models, especially with the performance leaps in version 2, transform data models into active gatekeepers. They don't just store data; they ensure the data is correct, coerced, ready for use, and able to transfer the data to other formats for interoperability.