Lesson 2
Side-by-Side and Unified Diff
Choose the right view when reviewing changes: aligned columns vs patch-style output.
Most diff tools offer two presentation styles.
Side-by-side view
Original text appears on the left. Modified text appears on the right. Matching lines stay aligned, while added, removed, or changed lines are highlighted in their column.
Use side-by-side when:
- You want to read both versions at the same time
- You are comparing configs or env files line by line
- You need to confirm whether a line moved, changed, or was replaced
Unified diff view
Unified diff shows one stream of output with prefixes:
--- original
+++ modified
DEBUG=false
-DEBUG=false
+DEBUG=true
DB_HOST=db.internal
-DB_HOST=db.internal
+DB_HOST=db.prod.internal
+CACHE_TTL=3600
Lines starting with - were removed. Lines starting with + were added. Context lines have no prefix.
Use unified diff when:
- You want patch-style output for notes or tickets
- You need a compact summary to paste into chat or email
- You are used to Git or code review diff format
Which view should you pick?
| Scenario | Better view |
|---|---|
| Reviewing env/config files | Side-by-side |
| Explaining a change to a teammate | Unified |
| Checking a few edited values | Side-by-side |
| Pasting diff into an issue comment | Unified |
Key takeaway
Side-by-side is for reading. Unified is for sharing. Both describe the same changes; they just optimize for different review tasks.
Switch views in the Text Diff Checker while comparing the same sample to see which one fits your workflow.