What is the difference between Cajun and Creole cuisine?
The previously accepted answer contains a good link, but not any information here on Seasoned Advice, so I thought I would write out a few things from my understanding after having developed an abiding interest in Cajun foods over the past decade.
Basically, Creole is a much broader term with a longer history. While it is perhaps inaccurate to say Cajun is a 'subset' area and culinary style, it is more geographically- and flavor-specific than just saying Creole. The history of people and region identified as Creole (on the American continents) goes back a long ways, and Cajun is a more recent phenomenon. Creole can also refer to other peoples and regions other than just in the South/Central parts of North America, though such use in the United States is a distant memory.
In the past century, the "Cajun" term has certainly attained an independent status as a self-identified people, region, and flavor -- the last no doubt owing to the flavor potency of their offerings. Which offerings, in my opinion, when consumed, are nearly always exquisitely enjoyable examples of perfection in the experience of food.
Both Cajun and Creole cuisines originate from French/European influence but there's a specific difference between them -
Cajun is French 'provincial' cuisine adapted by local workers for and with local ingredients.
Creole is French 'aristocratic' cuisine as practised in the better off households of the south and mimicking the influences of higher quality French/European cuisine but still having local Cajun influence using higher quality but still local ingredients.
Both cuisines have French, Spanish, Portuguese, Italian (European) influences, reflecting the previous occupants of the southern territories as well as African and Native American influences.