Seeders populate a database with known data. They are classes, usually in database/seeders, that can create reference data, development data, or test fixtures and can be run through Artisan or invoked from DatabaseSeeder.

Factories define repeatable model data blueprints, usually for generating realistic test or development records. A factory can create one model or many, define states, and relate models. In practice, seeders orchestrate what data is needed while factories make generating consistent model instances convenient.