When Discussing OBD Systems: Technician a Says the Main Difference

When discussing OBD systems: Technician A says the main difference between OBD I and OBD II are the trouble code standards.Technician B says OBD II systems must all operate in exactly the same way to help with diagnostics.Who is correct?

A) Technician A
B) Technician B
C) Both A and B
D) Neither A nor B