Difference between OxygenOS and CyanogenMod 13

Good day! I've just got OnePlus X phone, E1003 model. It is equipped with OxygenOS. Also for this model CM13 firmware exists. Please explain what firmware is more suitable. And what is fundamental differences between OxygenOS and CM13. I understand that OxygenOS v2.2.1 is built on-top of Android v5.1.1 and CM13 is built based on Android 6.x