Okay, the basic difference for me: Conspiracy theory tends to assume a human hand in control, or attempting to be; chaos theory, to keep it simple, says "Shit happens." sometimes, it isn't because anybody did it–or at least not the way that it gets presented.
Occam's razor is about unnecessarily multiplying entities, and is often fined down thus: If you have two choices, go with the more simple one, since that's most likely better. Not always, of course, but sometimes, as Freud was reputed to have said, a cigar is just a cigar.
A case in point:
A) A bunch of looney tunes religious zealots hijacked some jets and flew them into skyscrapers and the Pentagon and a field in Pennsylvania, killing themselves and a lot of innocent people.
Or:
B) A grand conspiracy, led by The Illuminati, the Elders of Zion, the Aliens, (chose one or all) caused the major governments of the world and tens of thousands of people to be complicit in a gigantic fraud, which included kidnapping a whole jetliner full of folks, secretly imprisoning them, faking phone calls to their relatives by actors good enough to fool long-time spouses, and then timing the impact of the jets to the second, to cover secretly-set explosive charges in the buildings that brought them down.
Or:
A) President Kennedy was killed by a nut-job ex-Marine who used a mail order rifle and then was himself killed by another nut-job on live TV in front of millions of people, an event I myself witnessed in black and white.
B) President Kennedy was killed by Cuban-Mafia-CIA-Aliens, sent by The Illuminati, the Elders of Zion, the Aliens, (chose one or all) who caused the major governments of the world and tens of thousands of people to be complicit in a gigantic whitewash, including among them senators, congressmen, judges, doctors, the President's family, and Bob's Your Uncle.
Why do people go down these B-roads? Partly, I believe it is a sincere attempt to make sense of things that sometimes seem so senseless that they short-circuit the mind. There must be a reason. It can't just be something as simple as a nut-job, can it?
Embracing chaos, even on a local level, is hard, and we continually try to sort it out.
Partially, it it because sometimes there is a grain of truth in the middle of things, just enough so that it makes it open a door. Maybe there was a second shooter on that grassy knoll. That's not beyond belief, is it?
Well, if that is true, then maybe the next step is true, too.
There is the slippery slope.
When I sold encyclopedia, if I could get the mark to answer yes to the first question I asked, a cascade of "yes" answers would logically follow–it was a carefully-constructed psychological sales pitch. I knew guys, who, if they could get in the door and get the mark to answer "Yes." to the first question, they could sell eight of ten.
There are real conspiracies, and just like somebody winning the lottery now and then proves that it is possible, these real ones open the door for frustrated people to wonder if there is more going on. And to make that leap: There must be.
Do I trust my government and the media to tell me the truth all the time? Even most of the time? Oh, hell, no! But I tend to attribute to stupidity a lot of things that conspiracy theorists attribute to malice.
I don't think we are that smart, folks. I just don't buy it that Saul and Abraham and Moishe are having nice glasses of Manischewitz in a mansion in Geneva, deciding who gets to be the next President or King, or how much gasoline will cost, or why it would be useful to fake a moon landing. It doesn't work for me.
I want to see hard evidence when somebody starts telling me these things, and not just because Rush said so. Because the weather guy on Channel 7 said that couldn't be a vapor trail behind that high-flying jet, it must be some kind of chemical? No, I'm not ready to hop on that bandwagon.
When the announcement came that Osama bin Laden had been killed, I turned to my wife and said, "You watch, some loon will say that he's been dead for years, on ice, and the Real Rulers of the World decided that the time was right to say we got him." And sure enough, there it was on YouTube.
I appreciate that my friends are sincere in their beliefs, and that they think they have good reason to believe what they do. But I need more.