The South Korea update is said to be based on Android 5.0.1 Lollipop, carry build number N910SKSU1BOB4, and be currently rolling out for Galaxy Note 4 users on SK Telecom. While there is no official rollout announcement from Samsung, the report suggests that it shouldn't be long before other major carriers in the country start pushing out the update.
Sammobile notes that the Android 5.0 update can also be grabbed via Samsung Kies software, and it is possible that the update may soon become available over-the-air.
As yet, there is no official changelog for the update, but users are reporting (via that changes include expandable lock screen notifications from stock Lollipop, refreshed Samsung apps with a Material Design, and more.
After the Android 5.0 Lollipop announcement by Google in October last year, Samsung had also hinted that the Galaxy Note 4 will soon get the Android 5.0 Lollipop update. The company had tweeted an image of the Galaxy Note 4 accompanied by a number of lollipops, suggesting that it is testing the Android update on the device. The tweet read, "Anyway you look at it, the #GALAXYNote4 Quad HD Super AMOLED display is pretty sweet. #NoteTheDifference."
However, the company has taken more time with the Galaxy Note 4 update than with the Galaxy S5, which began receiving the update for some variants as far back as December.