Plugin :: Pre -Operation & Validation

Hi Communities,

I've registered two plugin on " Account" entity.

1) Pre-Validation: Create Message-Whenever account created one task should be created.

2) Pre-Operation: Create Message- Whenever account created one contact should be created.

Here, If we Pre-Validation throw err in the sense Pre-operation will execute or roll back?

same vice-versa, If pre-operation will throw err in the sense Pre-validation will execute or not?

I got know that Pre-validation will not rollback?

Please clarify to me and when we want to Pre-Validation and Pre-Operation?

Regards

Dhanabal