How to compare two CSV files by rows and cells

CSV files look like plain text, but the meaningful unit is usually a cell. A whole-line diff can show a row as changed without telling you which field changed.

This becomes confusing when rows contain many columns, quoted commas, empty cells, or exported spreadsheet data.

Start by checking whether the two files have the same header row. If headers differ, fix that before reviewing cell values.

Then compare row by row and inspect changed cells with before and after values. Added rows and removed rows should be reviewed separately from modified cells.

Do not treat a full row change as a full data change if only one field changed. Do not ignore empty strings, null-like values, or whitespace if the downstream system treats them differently.

If the export order changes, row-by-row comparison may report many false changes. Sort by a stable key before comparing.