How efficient can be a user with a tablet versus a smartphone?

We can see at these days a large number of users utilizing a smartphone or a tablet as their daily working tool. Many professionals are changing the use of their desktop computers by using their mobile devices due to trends in their business. Thus, we can find more enterprise mobile apps that allow users to manage their companies using a mobile device in a more efficient and effective way and everywhere. This growing demand for mobile applications has become a challenge for current developers. We can find more and more enterprise applications delivered in three versions: desktop, tablet and smartphone. However, it is difficult to determine how productive a user can be in each version. In this paper we present a comparative usability study of one management mobile application designed for smartphone and tablet platforms for measuring the efficiency of the tablet version versus the smartphone version. We conducted a study with 8 participants to measure the efficiency of one mobile app and also measured the perceived usability using SUS questionnaire. This way, we obtained a ratio of the efficiency of using a tablet compared to a smartphone that could be significant for the development of future apps in small screens.