F-16 Block 70/72 is a new production aircraft with complete new advanced systems throughout the design, extended airframe life(12000 hours), and modern features when it comes to aircraft monitoring and other systems .
The F-16V upgrade modernizes older F-16s with advanced avionics and radar but does not change their fundamental block designation. Upgrading Block 52 aircraft to the V standard involves internal and possibly airframe life upgrades but does not make them Block 70/72 jets.
Lockheed Martin offers the Block 70/72 as a new aircraft separately from the V upgrade package. In essence, Block 70/72 is a new-build model, while the V upgrade is a modernization for existing aircraft.