Upload and download of Selective Merge operations: We are giving you an option during deployment to download the selective merge operations (changes) you performed. You can then upload them to another Jira instance or apply them as many times as you need to the same Jira instance.
Project scope allows you to run an integrity check on the configuration of selected projects. This way you can easily locate errors in a project or several projects without running a check on the whole configuration of your Jira instance.
Selective Merge allows you to download your deployment changes(operation performed by you) to configuration elements to a file and then upload and apply the changes/operations from the file to a Jira instance.