Structural JSON Comparison
A line-based diff reports reordered keys and reformatted whitespace as changes even when the data is identical. This tool parses both documents first and compares them structurally - added, removed and modified values are reported by their path, however the JSON happens to be formatted. That makes it the right choice for comparing API responses between environments or spotting exactly what a deploy changed in a config.
For plain text, logs or code, the Text Diff tool is the better fit - and if you are curious how diffing works underneath, see diff algorithms explained.