Smartphones are grown very fast nowadays than in the past. People from different ages are using smartphones to surf the Internet, organized activities, paly games, etc. while different parties are competing to design more learnable applications suitable for all ages. A set of learnability features of the applications will be considered in the comparison between two common operating systems of smartphones through classifying different criteria into design approaches of user interfaces.The main purpose of this research is to investigate the learnability feature in smartphones considering different operating systems (mainly Android and iOS) to evaluate the ability of each system to improve the learnability for the users. In this paper, we will compare two common operating systems for smartphones applications in terms of their learnability.More specifically, we are not interested in improving the learnability of smartphones applications by designing a new user interface for one of the smartphones operating systems, but rather we aim to describe the characteristics of learnability in both operating systems.This research is focused on two types of learnability: basic learnability and advanced learnability.