Studying the networked nature of social and cognitive aspects of learner interactions is the key to understanding how successful collaborative learning occurs in asynchronous online discussion forums (AODFs). Guided by network science and multiplex network analysis, this study compared the differences of network structure and properties between the social (learners as nodes and commenting on the others' contributions as edges) and cognitive (learners as nodes and explicitly quoting the others' contributions as edges) networks within an AODF. It additionally examined the differences of individual measures between these two monolayer networks and their integrated two multiplex networks. The two multiplex networks were respectively framed in superimposed and unfold approaches. Moreover, correlation analysis was conducted to examine the relationships between individual measures and learning performance across the four networks. Results showed key differences at the network and individual levels between the social and cognitive networks. The two networks had different compositions of participants, and students in the cognitive network occupied more central positions in general. Besides, certain individual measures in the multiplex networks were relatively higher and more related to learning performance than those in the monolayer networks. These results indicate that integrating multi-aspect information of collaboration may be more conducive to unveiling learners' interaction patterns in asynchronous online discussions.