What is the difference between them?

[gundogduyakici]

What is the difference between running a cron job with a service and running only a cron job? Because sometimes when I run it with the service the entity does not work and it does not work.

[tanya]

Long running in any job could happen because of Fatal error. Make this job Pending and run cron.php in terminal

[gundogduyakici]

I understand. Does the service always work for an entity? What exactly is the purpose of the service?

[yuri]

No. Service is not always related to a specific entity type. Any logic you would like to separate you can put into a separate service class.