difference between Custom Setting Type "List" and "Hierachy

Hierarchy custom settings can be configured at varying user specificity levels under a single name; the platform will look for the most specific configuration first, then fall back / inherit to the least specific:

• setting per user,
• setting per profile,
• setting for whole org,

Hierarchy custom settings are easily retrieved in Visualforce: {!$Setup.Setting__c.Field__c} and will be resolved according to the current user context.

List custom settings have user-independent values, retrieved under multiple names. For example, you could use several configs to hold the credentials for a web service callout so that you can swap the endpoints:

• setting for development environment,
• setting for volume testing environment,
• setting for production environment,

List custom settings need to be accessed using a controller if you want to avail them on a page, for example return ListSetting__c.getInstance('dev').Field__c;