Both Creole and Cajun seasoning are similar and are used as cooking terms in interchangeably.
Creole is made with more herbs ranging from oregano to basil and paprika whereas Cajun seasoning does not.
Cajun Seasoning just like Creole Seasoning is made with garlic powder, onion, black pepper, and Cayenne pepper but the Cajun seasoning doesn't contain the oregano, basil or paprika like Creole seasoning does.
Both Creole and Cajun seasoning can work in recipes that call for either but the results may not be as good if you just used the correct seasoning.
Still both creole and Cajun seasoning are good seasonings that go well with just about every dish you can think of or make.