We declare the first results of the representation of the differences between the proper
motions UCAC4-PPMXL, XPM-UCAC4 and XPM-PPMXL by vector spherical harmonics in the 10 to 16 J mag range (2MASS photometric system). It was found that the PM systematic differences vary from - 15 to 15 mas/y. The proper motion XPM catalogue has the least systematic deviation from the PPMXL and UCAC4 for stars fainter J=13. The values of spin for UCAC4 on PPMXL are 5 times less than values for XPM on PPMXL and UCAC4. Magnitude equation is clearly seen through dependence of the decomposition coefficients and mutual spins on J magnitude. The influence of low order vector
spherial harmonics on the determination of the Ogorodnikov-Milne coefficients is clarified.