Line Set Comparison Inspector

What changed between two blocks of lines

Comparing 'alpha / beta / gamma' against 'alpha / beta / delta' shows 1 line added and 1 line removed: '- gamma' and '+ delta' -- 'alpha' and 'beta' appear in both versions and aren't flagged as changes at all.

This is a set-of-lines comparison: it identifies which lines exist in one version but not the other, regardless of their position -- a line that simply moved to a different position without changing its text wouldn't show up as added or removed here, only lines whose actual text content differs between the two sets.

The '-' and '+' prefixes follow the same convention as most diff tools (removed and added respectively), making this output format familiar if you've worked with git diff or similar version-control diff displays.

Why this isn't a full unified diff

Set-of-lines diff. Repeated lines and moved blocks are not a unified diff. A real unified diff (like git diff produces) tracks line position and context, correctly handling cases like a duplicated line appearing twice in one version but once in the other, or a whole block of lines moved to a different location without changing their content -- this simplified tool treats lines as a set, which doesn't capture position or duplicate-count differences.

If Version A has a line appearing twice and Version B has that same line appearing once, a full diff tool would show one instance as removed; this set-based comparison, focused on which distinct lines exist versus don't, handles that case differently.

For source code specifically, a real diff tool that understands line numbers and context (not just presence/absence) is more useful for actually applying or reviewing a patch -- this tool is better suited for quick, simple before/after text comparisons than for code review.

Related comparison and structured-diff tools

For comparing two JSON objects or structures rather than plain text lines, the Structured JSON Diff Viewer is built specifically for that structured comparison.

If you're comparing two lists of installed Python packages specifically, the Pip Freeze Diff Tool applies similar line-comparison logic to that specific use case.

Frequently Asked Questions (FAQ)