They are quiet different. I am not familiar with the Fat Tuesday. But I suppose both of them is wonderful.
Chinese New Year is a celebration for the new year in Chinese Lunar Calendar. People gather their familiy for celerating the coming new year. All people hope fortune in the beginning of new year. So, there is much traditional custom in Chinese New Year. Such as gathering, giving packet money, inter blessing with some lucky words, worshipping and others. People hope these can bring a fortune to them in the new year.