“…By contrast, the goal of a copyedit is to address flaws on a very technical level – to make sure the writing that appears on the page is in accordance with industry standards. This is like an incredibly high-end proofread.
A copyedit: Corrects spelling, grammar, punctuation, and syntax
Ensures consistency in spelling, hyphenation, numerals, fonts, and capitalization
Flags ambiguous or factually incorrect statements (especially important for non-fiction)
Tracks macro concerns like internal consistency.Internal consistency means your plot, setting, and character traits don’t have discrepancies.
For example if on page 41 you write: Rosemary wore her blond hair in a bun, and then on page 67 you write Rosemary brushed her long black hair, it’s a copyeditor’s job to point that out.”
Source: What is the Difference Between Copyediting and Line Editing?