A production environment is the public-facing view of your website. It is where you install StagingPro, and any changes which StagingPro makes to the production environment means mean that your live website will be affected.
A staging environment (stage) is a nearly exact near replica of a production environment for software testing. Staging environments are made to test codes, Code builds, and updates require Staging environments to ensure quality under a production-like environment before application deployment to the production environment.