The Client and Services build can differ and still work as expected. It is best to keep them within the same minor build branch.
For example 126.96.36.1994 for the client and 188.8.131.521 are fine but 184.108.40.2064 and 220.127.116.112 may not be. 6.4.1.x should be upgraded to a build within the 6.4.2.x range.
If you are in doubt on this, please contact support to verify that it is ok.