Feature as the name suggests - When we are planning for release then it may have one or more features which are being added to the product. Feature is a chunk of functionality that delivers business value. Features can be one large story or group of stories.
Features can be broadly grouped into Required, Desired and Preferred. Priority of feature depends on these groupings.
Example of a feature is : Provide the ability for customer to work offline (without internet connectivity) on software.
To build this feature, we may need to create one or more stories depending upon the details of requirements.