I spent last week in New Orleans, eating such things as beignets (square-shaped French donuts), pralines (sickeningly sweets patties of pecans in a concoction made of sugar, evaporated milk, and vanilla) and drinking cafe au laits and frozen daiquiris (daiquiri bars litter the city and the daiquiris come in many different flavors). Unfortunately I wasn't able to try the Cajun and Creole -- the two terms are distinct and not interchangeable, but I'll get more into that later -- food that New Orleans is known for, due to my vegetarianism, but I did enjoy learning more about the culture.
I was down there visiting an old friend of mine, Kijai, who's been living there the past year, and fortunately for me, between her and her roommate Kristen, I was able to see a lot of New Orleans that the average tourist doesn't get to see (since, it would seem, most tourists don't venture further than the French Quarter and the streetcars). Kristen was particularly informative about the culture, being Cajun herself, and born and bred an hour and a half southwest of New Orleans on the bayous.
Kristen seemed proud of her Cajun history and very informed -- though she looked and talked anglo, with blonde hair and only the slightest Louisiana accent. She told me how the Cajuns were exiled from Canada (then a colony of Great Britain) due to their refusal to give up their Catholicism "in 1755. I'm not too good with dates, but I remember that one", and shipped along "like slaves", never finding a place of acceptance until they reached the bayous of Louisiana. She told me, "in France we lived on the coast of Normandy, and in Canada we lived along the coast. So when we arrived in Louisiana, we felt right at home. The Cajuns were good at a lot of things that they're now having problems with."
So New Orleans, to set things straight has a bit of the Cajun influence (French Canadians, or a particular ethnic group called Acadians - with the a- dropped from the beginning through aphesis, and the "cadians" slurred much like the American perjorative "injuns" from Indians), and it also has Creole influence.
In order to keep this shorter than a book (which indeed the subject lends itself to) I'll summarize succinctly. In Louisiana, "creole" is a term used to describe people of mixed French, Spanish, African, and Native American descent (they can be a mix of some or all, and some include other heritages). The word itself derives from the Spanish word criollo, which had evolved from the word criado, a past participle of crear, meaning "raised" (and ultimately traces back to Latin creare, to rear or create.) While Louisiana was still a French colony, this term was used to refer to people who were born there, as opposed to immigrants.
On an interesting notes, Creoles of color in New Orleans felt threatened by the Civil War. New Orleans at that time was a three-tiered society, and free people of color worried about losing their higher status after enslaved Africans were set free -- which indeed did transpire.
I gathered much of this information from talking to people in New Orleans, as well as the lovely Wikipedia. I'd highly recommend further reading on the fascinating history and culture of New Orleans. Kijai personally recommends the essays of Andrei Condrescu.