The terms were more or less synonymous at that time.

they still are :p

One of the oddest spin off affects of intense Diplomacy players is the effect it has when you play other games. Dip players tend to bring in Dip into just about any other game with multi players. For example I remember playing Settlers of Cataan and arguing that we should not have open trades.
Also in a game of Monopoly I tried to negotiate a DMZ in two places where we agreed not to build hotels on a certain place. Then of course there was the deal where I turned to a player who was low in cash and said, "Look you have less than a 50-50 shot at avoiding the leaders hotels,
so why not sell to me all your assets for a dollar so that if you land on it then he will not get it and you can stab him that way. If you don;t land on it I will sell you it all back for 100 dollars so as to make a little on the Holding Trust Fund. The tournament director thought this was hyterical, but ruled it as "Diplomacy is not allowed in a Monopoly game"

I find myself using "diplomacy speak" when in situations where i feel i am expected to say yes, but I don't intend on following through. For instance if someone i don't really like asks something along the lines of, "Hey, want to come to the bar you don't like and hang out with me and some others that you don't particularly care for?" and in the spirit of politeness I need to agree. So, I say, "Sounds like a plan!" or "that could be done."

Additionally, my international law class has been made all the more interesting by comparing the real laws with what i normally do in diplomacy. Terms like uti possidetis have rarely found such deep understanding in a law student.

I have found the under-handed strategizing and decisively analyzing an opponents motivations very handy in my work negotiating a Memorandum of Understanding with an ex-partner, an attorney, after he stabbed our business by stealing the Corporate Minutes Books.