What are the types of custom settings in Salesforce?

Hierarchy Custom Settings: It uses a built-in hierarchical logic that allows you to customize settings for specific profiles or users and this logic evaluates the organization, profile, and user settings for the current user and returns the exact or lowest value in hierarchical rank. Only this setting is available in Workflow Rules and Validation Rules.
List Custom Settings: It is very similar to the way custom objects work. It provides a set of static data that can be accessed across your organization. If you want to avoid governor limits, put that data in a list custom setting. And in list custom settings, we can access that data without writing SOQL.