IMO cats from a lake get fatty and have a musty taste to them whereas a cat from a river seems leaner with a better taste
You have got to cut the fat off the top of the back of a pond/lake catfish or they will have a bad taste. Also, go ahead and throw the belly pieces away.
As for mudcats, I ate them as a kid when we caught them out of Caney Creek. I bet I could tell the difference, no problem.
Also, catfish seasoned and cooked by someone that knows what they are doing can rival any other fish.