Many studies in literature have compared peer e-feedback/comments to traditional peer feedback/comments to see whether one medium of providing feedback should replace the other. However, few studies investigated to see whether two modes of commentary activities positively affected the students' writing quality, instead of just comparing one to another. The literature failed to investigate the extent to which each had effects on students' writing skills. The purpose of this study was to fill this gap. The current study employed quasi-experimental research with control and experimental groups to study the issues. Seventy-two native Vietnamese students from two intact classes at Ho Chi Minh City University of Science who had ever obtained this kind of training activities participated in the study. The training procedures for both groups were similar except one conducted face-to-face peer comments on papers and the other on Facebook social network. Data collection was from pre- vs. post-tests rated by inter-raters and analyzed by the ttests of SPSS software. The findings of the study revealed that peer commentary activities of both groups had significant impacts on students' writing quality; however, the peer e-comments outperformed the traditional peer comments.