Since the world is moving to the era of mobile Internet computing, the business conducting over the mobile devices became popular. Not only smartphones, but tablet computers also present a variety of new opportunities for business with their technological ability. The research question of this paper is “What are the differences in M-Commerce application between tablet computers and smartphones?”. Three comparison case studies of M-Commerce applications show the differences in the design for tablets and smartphones. The paper contains the introduction, the literature review, the information of current devices in market, the comparisons of M-Commerce applications, the discussions, and conclusions.