The booming development of informal learning resources such as those available online in the Web 2.0 ecosystem, the generalization of learning methods centred on the students in institutions and the emergence in higher education of new models of learning platforms, such as Personal Learning Environment (PLE), in parallel to the now traditional Learning Management Systems (LMS) question the education institutions on the support and technological resources they can provide to their students to support them in this new and challenging context. A solution could be a PLE enabler that provides a framework to help students building their own PLE and bridges formal and informal learning activities. In this paper we describe a comparative study of two PLE environments in order to understand 1) what are the core characteristics, components and/or functions of a PLE enabler and 2) why a student will transform, or not, a PLE enabler into his own PLE.