If two meters are not of the same manufacturers, readings will likely not correspond, because of the different calibrations used. Often, there are different species and temperature correction factors.
Even readings on two meters of the same manufacturer may vary. Assuming both meters are electrically correct, the difference usually can be attributed to use of different electrodes, pin penetration, and species and temperature corrections. When meters are used for lumber inspections by vendors and buyers, the two parties should have a basis for comparing readings obtained with the instruments they are using.