Why do I have a 'Staging' and 'Production' embed code?

In DTM, the 'Staging' embed code will always reference the staging library file which represents all unpublished and published items within the property. The 'Production' embed code will always reference the production library file which represent only the published items within the property.

For more information on the publishing workflow, see documentation here: https://marketing.adobe.com/resources/help/en_US/dtm/publish_workflow.html