As written feedback is an indispensable component of instructing and learning process, the implementation of effective feedback plays a key role in improving non-English majors’ writing skill. Peers and automated writing evaluation systems are new, main sources of feedback providers in college English writing. This paper compares three feedback conditions: individual and group modes in peer feedback and automated feedback. Analysis is made on distribution features from feedback types, dimensions of assessment rubric, aspects of organization and linguistic performance, and reflected attitudes. The findings indicate automated mode and group mode take turns dominating in non-corrective feedback and corrective feedback; group mode takes the lead in both direct and indirect feedback; individual, group and automated modes underemphasize global feedback. Dimensions are found to centre on linguistic performance, followed by organization, content and format, differences and similarities of specific aspects and attitudes are also found in all three modes. Further investigations are undertaken into students’ perceptions towards peer feedback and automated feedback, with their respective merits and demerits summed up. On the basis of all the findings, key elements of sociocultural theory are explored to provide multi-dimensional feedback scaffolding for students of lower-intermediate level in facilitating college English writing.