The purpose of the study is to provide an analysis of lexical, syntactic, and cohesive features, which were utilized to distinguish written products of L2 writers in the individual writing task from those in the group writing one using Coh-Metrix. In addition, the study attempts to explore linguistic differences in their written outputs with regard to their L2 proficiency and the correlationships between receptive lexical knowledge and productive lexical knowledge. A total of 105 Korean university students participated in this study. Results show that L2 learners’ written outputs varied in several variables used in this analysis such as lexical diversity and word frequency. L2 learners in the individual task yielded more cohesive texts, and they were able to incorporate more difficult words into their written products. Meanwhile, learners in the group task produced longer texts with using more logical and temporal connectives. When proficiency level was considered, L2 learners at the advanced level did not produce more cohesive texts, but instead produced more syntactically complex texts. The scores of productive lexical knowledge in the individual task positively correlated with those of receptive lexical knowledge from two different vocabulary tests. Meanwhile, the scores of productive lexical knowledge in the group task did not yield the similar results. The results implied that Korean university learners in the individual task were more task-oriented and produced a better written output.