As the recent focus of using E-Learning Systems (eS`s) has been increased and Internet has become more accessible, the quandary of designing efficient eS`s becomes more severe. The diversity of users within a group, sharing an eS having their individual abilities, interests and needs challenge the designers of an eS`s with heterogeneous needs for Adaptive User Interfaces (AUI`s). These tribulations of designing eS`s resulted in the creating of Adaptive E-Learning Systems (AeS`s) which serve a specific set of user characteristics, in which the system or the user render its components and interface according to different requirements. This study has offered a brief overview of the eS`s and the AUI`s. In the same time we have pointed out existing and major problems for the designing of eS`s. Hence we have conducted a research study for the profiling of eS students from three different countries UK, India and Iraq. In particular we have explored the collected data and what it tells us about the implications and variability of designing AeS`s. Subsequently from this study we made an exhaustive conclusion followed by usability requirements summary, which indicates the required usability level for each country. Findings show that the differences in the general, user and usability characteristics of the students profiles, can principally affect the designing of eS`s. Eventually from the derived analysis and conclusion, we argue that AUI`s is a major component and the core of AeS`s and there is an existent need for precisely defining user profiles by following a user centered approach.