This is two distinct soup/stew dishes with thousands of variations.
I like them both. Seafood gumbo is usually a freshly prepared dish while the turkey and sausage based variations often follow a day after that dish is served as the entree. Rice is the traditional base over which the gumbo is served.
I believe the best seafood gumbo in town can be had at
Harbor Seafood on Williams Blvd in Kenner, just north of the airport. It is a totally casual neighborhood bar and restaurant that draws traffic from around the city. Be prepared to wait a few minutes for a table or you can just sit at the bar and chow down. If you want to spend more go to the French Quarter. You won't be disappointed.