I really haven't seen too many of either lately to make any distinctions yet...
But Jeffy has an extremely distinct style of writing you can just feel in every show he's been involved with. For example, he does a lot of episodes about the olympics (Captain N for example, the episode was Videolympics), and he had a lot of scripts titled "Lights, Camera, ________" (Lights camera Muppets, Lights Camera Littles... etc)
He was one of the best and worst writers of cartoons there was. Sometimes he really did a great job, sometimes he just did pretty cliche'd stuff. I am a fan, make no mistake, and I have his book. He really has a good handle on the characters of ANY show he has done. Especially TMNT, when he was given the horrible last season when the original writers decided to make horrendous plots cuz they didn't think the show would last one more year.