It can make worlds of difference! It can raise the working pressure of a round beyond safe limits in some cases. Look carefully at the components used in the two manuals - are they exactly
the same? Are one or more of the components (case, powder, bullet style/manufacturer) different? These seemingly insignificant things can change a safe load into a dangerous one.
In other loadings it may not make much of a difference at all - but you can't tell until you touch them off.