When whitespace and line endings matter
Noise reduction is a viewing choice, not proof that two files are interchangeable.
Identify the source of a large diff
Files copied between systems may differ in line endings, trailing spaces or final newlines even when the sentences look the same. Start with the strict comparison so you know differences exist. Then use whitespace-related options to inspect the meaningful edits more easily. Record which options are active before sharing a result, because another reviewer using strict settings may see additional changes.
Do not ignore syntax by accident
Indentation is meaningful in Python and YAML. A tab can be required in a make recipe, and spaces inside a quoted string are data. The two strings below do not contain the same characters even though repeated spaces are easy to overlook. Hiding a difference in the comparison view should not be interpreted as permission to remove it from the source.
"New York"
"New York"Confirm the destination’s requirements
For prose, trimming accidental trailing spaces may be harmless. For patches, signed files or exact fixtures, byte-for-byte details may matter. Choose the normalization intentionally, apply it outside the comparison when appropriate and then rerun the diff. Preserve an untouched version before any cleanup. If a file appears as one enormous line or contains replacement characters, check the source encoding instead of treating the display as an ordinary edit.