What is the difference between a role hierarchy and sharing rules in Salesforce?

In Salesforce, a role hierarchy is a system that defines the levels of access that users have to data based on their position within the organization. Users higher in the hierarchy can access the records of users below them in the hierarchy.

On the other hand, sharing rules in Salesforce are used to extend access to records that a role hierarchy does not grant automatically. Sharing rules are set up to give specific users or groups access to records they would not normally be able to see based on their role in the hierarchy.

While the role hierarchy controls access based on job position, sharing rules allow for more specific and customizable access to data, increasing flexibility in sharing data within the organization.