Depending on the nature of comments made during peer review of academic writing, students may be able to evaluate and revise their performance. Therefore, it is essential to explore how the content of comments affects student writing. Since peer review is a process of interaction, it is critical to understand how comments affect student academic writing performance at both group and individual levels. This study examined online peer review of 68 master's and doctoral students in the scientific writing course who divided themselves into dyads. The study evaluated the effect of different feedback categories on the writing scores of five different sections of a scientific research manuscript. Comments can be broadly categorised as elaboration, verification, and general. Their focus can be further divided into abstract general, criteria general, criteria specific, and language. The results revealed that different types of feedback affected dyadic and individual writing performance in similar ways. Verification feedback had a more pronounced effect on student writing performance than elaboration and general types of feedback. The findings also suggested that verification feedback had different effects on writing in different manuscript sections. For example, an increase in the frequency of verification feedback was associated with improved scores on the abstract, but decreased scores on the results section.