One odd thing I noticed, that was already discussed at length in several forums, is that kobolds are depicted as dog-like creatures of small stature in the B/X rules. This same description is carried to the Mentzer basic set. However, the Monster Manual published in 1977 is somewhat different. Here's the complete description:
"The hide of kobolds runs from very dark rusty brown to a rusty black. They have no hair. Their eyes are reddish and their small horns are tan to white."
This suggests a demonic imagery of sorts. I don't know if this was intentional or the result of some other editorial decision, but it further set apart the two game lines: D&D and AD&D, although, truth be told, the Monster Manual is completely compatible with the former rules.