The whitespace preset compares `name: Ada` with trailing spaces and `role: editor` against lines whose edge and interior spacing differ. Exact mode exposes those character changes as line removals and additions. Ignore-all-whitespace mode matches both pairs while the table still shows the original spellings. This demonstrates why normalization belongs to a visible option and why ignored differences must not be mistaken for changes that no longer exist.

Exact mode records both changed lines

Load the preset and select Exact. The left first line contains two trailing spaces that the right lacks. The second pair differs in the run between the colon and `editor`. Neither comparison key matches, so the shortest script contains two removals and two additions with zero retained lines. The source panels and result preserve spaces even when they are difficult to see. For detailed invisible-character inspection, use an editor that can render whitespace glyphs; TextDiff does not invent such glyphs in user text.

Ignore-all-whitespace matches keys, not display text

Choose Ignore all whitespace and compare again. Removing Unicode whitespace from each line key turns both first lines into `name:Ada` and both second lines into `role:editor`. The result reports two retained lines, no removals, no additions and 100% configured line similarity. Because matched source spellings differ, the result can show the original and revised forms together. Copying the unified view uses the revised spelling for a retained-by-rule line, so always keep the selected mode in mind when reviewing copied text.

Choose the narrowest rule that answers the review

Use edge-whitespace mode when indentation or accidental trailing spaces are known noise but internal spacing still carries information. Use all-whitespace only when spacing anywhere inside a line is outside the question. For source code such a broad rule can hide meaningful token separation, and for prose it can hide intentional typography. Return to exact mode before approving an authoritative revision. The modes are filters for visual investigation, not a declaration that the ignored characters are universally irrelevant.