Android kernel branches -

i couldn't find info anywhere on internet. can explain difference between following 2 branches? both belong nexus 6p (angler) unclear 1 real kernel pushed device. "mr" major release , therefore ahead of other branches?

https://android.googlesource.com/kernel/msm/+log/android-msm-angler-3.10-nougat-mr0.5/

https://android.googlesource.com/kernel/msm/+log/android-msm-angler-3.10-nougat/