What is the difference of mark in text and margin proofreading?

Margin proofreading focuses on problems that can be corrected without affecting the text itself, such as typos, grammatical errors, and formatting issues such as spacing, indentation, and capitalization.

Text proofreading, also called copy editing, involves making editorial changes to the actual content, such as restructuring paragraphs, revising wording to improve readability, and checking for consistency in style, tone, and factual information.