Previous studies have been done to research the effects of different electronic feedback (e-feedback) modes of helping English as a foreign language (EFL) students improve their writing. The purpose of this study was to employ online peer feedback (OPF) and automated corrective feedback (ACF) to assess EFL learners' writing performance in the areas of sentence complexity, grammatical accuracy, and lexical density. Our major findings suggest that OPF is potentially more useful than ACF in improving sentence writing, making fewer grammatical errors, and producing more types of lexical items. Nevertheless, we also found that the majority of students favored the use of ACF for the purpose of producing a richer vocabulary. Less skilled writers tended to make greater improvements than higher-skilled writers in producing more sentences and lexical items after OPF use; however, the difference was not statistically significant. Based on our research results, we discuss and present the implications of these findings for pedagogical instruction and future research.