SheetCompareHeader row
The first row of a table that names each column. It turns positional data into named fields and is what tools match on when comparing files.
A header row is the labels at the top of a table, name, email, amount, that give each column meaning. Most CSV and spreadsheet files include one, but it is a convention, not a rule, so a file can start straight into data. Knowing whether a header exists is the first decision any parser makes.
Headers matter most when comparing files. If two exports list the same columns in a different order, matching by header name (rather than by position) lets a diff line them up correctly, so a reordered column isn't reported as a wholesale change. SheetCompare matches on header names for exactly this reason, which is why column order doesn't have to be identical between your two files.