This question starts an interesting discussion on one of louisianacajun.com's forums. I don't see why there can't be "black" Cajuns and "white" Creoles but the popular view is "black" Louisiana French people are Creole and rural white Louisiana French people are Cajun. This is the case around here. It's interesting to see how the labels are defined by different people.
Creole or Cajun?
T-Trahan is from Lafourche Parish. He speaks his area's Louisiana French well and it does not sound like the Pointe Coupee area. T-Trahan's ancestors are all African. He is a known cook and makes the best gumbo in the parish. Many of his neighbors have Acadian ancestry but their gumbos are not as good.
T-McGee is from Evangeline Parish. He speaks his area's Louisiana French well and it does not sound like the Pointe Coupee area. T-McGee's ancestors are mainly Irish and French. He has no Acadian ancestors and neither does his neighbors. He does not have any African ancestors.
T-Broussard is from Vermilion Parish. He speaks his family's French well. The majority of his ancestry is Acadian, except for his g-g-great grandmother who was of African descent. In Ville Platte, people would say he was "bright," meaning he has light skin.
Ok, around here the answers would be simple. T-Trahan and T-Broussard would be Creole and T-McGee would be Cajun. It doesn't make sense unless the definition of Cajun means a rural white Louisiana French person and Creole means a rural or urban "black" Louisiana French person. A good article to start with is Cecyle Trepanier's The Cajunization of French Louisiana: Forging a Regional Identity. Also, T-McGee and his distant cousin, T-Guillory, also of Evangeline Parish, both share many of the same ancestry -- Fontenot, LaFleur, Guillory -- except T-Guillory has African ancestry and T-McGee has Irish. They speak the same French and make their gumbo the same way. Again, who is Cajun and who is Creole?