It is not the same. “Documentation,” through the United States Coast Guard, is federal documentation. The national form of boat registration in the United States, it applies to all fifty states and not just one state individually.
Documented vessels cannot have titles. Instead, they have a Certificate of Documentation.
This Certificate admits vessels to particular restricted trades, which include the fisheries and coastwise trade (transporting people and/or merchandise). Documentation also provides for commerce between states which is unhindered and, for international purposes, provides conclusive evidence of nationality.
Some states require documented vessels to also be registered with the state. Use the following link to apply for vessel documentation.