The "green cover" versions was substantially edited and modified by Tom Moldvay and released several months after the original orange version was recalled and destroyed.
Palace of the Silver Princess: DM Notes replaces the preprogrammed adventure section, offers a different background, and adds some wilderness encounters for the "green cover" Palace of the Silver Princess.
The orange edition was released and recalled in a single day and very few, almost certainly less than one hundred, authentic originals exist of this version. The orange version is widely known because it was released in 2000 as a free PDF download on the Wizards of the Coast website.
See the entry for B3: Palace of the Silver Princess (Orange) for more about the history of this module and other editions.