Recently, it is noted that the teacher’s learning community and lesson studies are being emphasized as part of the growing literature regarding education policy. However, there is a burden of building an attitude of cooperation among the teachers regarding the lessons, and there is mounting concern over the possibility of professional development without education experts. This study compares and analyzes the significance of various aspects of cooperative interactions among teachers in two elementary schools in Gyeonggi-do, South Korea. The examples of the two schools identified in this study are similar in that they study the lessons available and accessible in the teacher’s learning community. However, there are subtle differences internally to the means and results of these lessons. In the study, the participants of Community A focused on the development and sharing of learning tasks in the learning process. The collaboration, which is characterized by critical companionship, was implemented with the Community A participants in the study. Conversely, the participants in Community B focused on associated teaching practices, and cooperation was implemented in the process of trial and error. A review of these cases raised the possibility of professional development through the teacher’s learning community in the general school. Moreover, the results provided implications for the lesson study through the entire associated teacher’s learning community.