In the Raman free-electron laser as a high-power radiation source with megawatt in millimeter and terahertz wave ranges, the stability of relativistic electron motion is of importance for the performance of the device. By making use of the reported MIT experimental data and Kolmogorov entropy, comparative study is carried out on the stability of the relativistic electron motion in a Raman free-electron laser with positive/reversed guide magnetic field. Results show that the wiggler adiabatic field has trivial influence on the stability of electron motion but substantially affects the electron motion itself in both positive and reversed guide magnetic field cases; the self-field of the electron beam deteriorates the motion stability in the case of a positive guide magnetic field, but favors the motion stability in the case of a reversed guide magnetic field.