As for the distinction of Devils versus Demons in Dungeons & Dragon the first mention of the idea occurred in the 6th issues of the Strategic Review in Feb 1976. The article was "The meaning of Law and Chaos in Dungeons & Dragons and their relationships to Good and Evil."
There was a chart and in the lower left (Lawful Evil) corner was marked Devils. And that is pretty much it until the release of the AD&D Monster Manual. They are not even listed on succeeding figure in the same article which places then current D&D monsters on the alignment graph.
Here is what Gygax said on the topic.
Quote:
Many questions continue to arise regarding what constitutes a “lawful” act, what sort of behavior is “chaotic”, what constituted an “evil” deed, and how certain behavior is “good”. There is considerable confusion in that most dungeonmasters construe the terms “chaotic” and “evil” to mean the same thing, just as they define “lawful” and “good” to mean the same.
This is scarcely surprising considering the wording of the three original volumes of DUNGEONS & DRAGONS. When that was written they meant just about the same thing in my mind — notice I do not say they were synonymous in my thinking at, that time.* The wording in the GREYHAWK supplement added a bit more confusion, for by the time that booklet was written some substantial differences had been determined.
In fact, had I the opportunity to do D&D over I would have made the whole
business very much clearer by differentiating the four categories, and many
chaotic creatures would be good, while many lawful creatures would be evil.
|
*If you read Playing at the World, Hawk and Moor and other accounts of gaming in the Upper Midwest is that the whole Law and Chaos represented two opposing side in a campaign. And that campaigns has players on the side of Law and players on the said of Chaos. The neutrals were the folks that either side could try to recruit. Some Lawful players were quite shifty and sneaky, and some Chaos players were quite honorable. However as a rule the side of Law were generally on the side of civilization and the side of Chaos had monsters and barbarians.
As tabletop roleplaying developed into its own thing is seems natural to me that something more nuanced was developed.