Gumbo is a Creole dish that has been adopted by Cajuns.

Creole gumbo contains stock, meat or shellfish, the so-called "holy trinity" of celery, bell peppers and onion, and is thickened with okra, filé powder or roux and is usually served over rice.

So how can you tell the difference between Creole and Cajun gumbo?

Creole gumbos tend to use a paler roux and sometimes includes tomatoes (Cajun gumbo never does).