This study examines the distribution of peer review in face-to-face and mobile-mediated peer review groups and their effects on students' revision skills and academic writing development. Seventy-two first-year English for academic purposes (EAP) students participated in an 18-session IELTS academic writing course in a Canadian university the mobile-mediated peer review group (MMPR) used Telegram to exchange peer comments synchronously, while the face-to-face peer review group (FFPR) did peer review in the classroom. An adapted analytic scheme ("Journal of English for Academic Purposes," 2, 193-227, 2003) and the IELTS academic writing assessment criteria were used to conceptualize the peer comments in terms of frequency, area, type, nature, and IELTS assessment categories. Results indicated that the total number of comments, the percentage of revision-oriented comments and actual revisions made by the MMPR group were statistically more significant than those by the FFPR group. Furthermore, the MMPR group made more local revision-oriented comments than that of FFPR. However, the revision-oriented suggestion in local areas was the most distributed type of comment made by both groups. Regarding the IELTS assessment criteria, the FFPR group made more comments on task achievement and coherence and cohesion, whereas the comments made by the MMPR group targeted more lexical resources, and grammatical range and accuracy. In addition, the results showed that both MMPR and FFPR groups developed their IELTS academic writing skills while the MMPR mode of collaboration outperformed the FFPR.