Release if of 2 types- external release and internal release
 External release is version where as internal release to 
testing team is build.

addition of new feature to an application is called version
build means aggregation of all defect fixes and features 
that are present in a product

When the application delivered for testing is called as 
build.
when the application delivered for client is called version.

Version refers to the Application(After modifying according 
to change which is either defect fix or other)
Build refers to fixes of defects to test the application 

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