What is the difference between configuration and customization in Salesforce.

Configuration:

•Configuration means providing a user defined values which will enable a given feature or module to function.
Example: Email setting is an example of configuration.
•salesforce users can configure CRM application. Marketing User can enable few tabs which are not available for Customer support people.
• Adding a new field to a given salesforce object is configuration.
• adding a new field which will use formula to perform some result is configuration

Customization:

•Any feature or functions which are not available as a part of application and the application needs to extend refers to customization.
•Despite you configured the things there are few actions which are not achievable and it results into adding some custom code, which results in Customization.
• Adding triggers on the object to perform some action is called customization
• Adding Apex Code which will generate a vCard from a given Contact is called Customization.