Sandboxes are critical for large and mid-size customers to develop and test configuration changes without impacting end users on production. Winter '10 brings the beta release of Sandbox to Production which allows a non-technical admin or business analyst to copy supported types of changes between sandbox and production organizations, or between sandboxes, right within the app. You can now move any changes, apps, configurations with just a few clicks.

A change set is a means by which one organization can send these customizations to another organization. For example, you could create a new object in a sandbox organization and send it to your production organization using a change set. Change sets can only contain modifications you can make through the Setup menu; therefore, you can't use a change set to upload a list of contact records. In other words, change sets contain metadata, not data.