How to See the Differences Between Two Branches in Git

Before merging a feature branch, reviewing a pull request, or understanding what changed between releases, you need to see what differs between two branches. Git provides several commands to compare branches at different levels of detail.

TLDR: To see differences between branches, use git diff branch1..branch2 to show file changes, git log branch1..branch2 to show commit differences, or git diff --name-only branch1 branch2 to list changed filenames. The two-dot syntax (..) shows differences, while three-dot (...) shows changes since the branches diverged.

In this guide, you'll learn how to compare branches effectively in Git.

Prerequisites

You'll need Git installed on your system and a repository with multiple branches. Basic familiarity with Git branches and the diff command will be helpful.

Basic Branch Comparison

To see all changes between two branches:

# Show differences between main and feature branch
git diff main..feature-branch

# Or without the dots (same result)
git diff main feature-branch

This shows the actual code changes - additions and deletions in all files.

Listing Changed Files Only

To see which files differ without showing the changes:

# List files that differ
git diff --name-only main feature-branch

# Output:
# src/app.js
# src/auth.js
# tests/auth.test.js
# README.md

This is useful for getting an overview without detailed diffs.

Showing File Changes with Status

To see filenames with their change status:

# Show files with status indicators
git diff --name-status main feature-branch

# Output:
# M    src/app.js        (Modified)
# A    src/auth.js       (Added)
# D    old/legacy.js     (Deleted)
# M    README.md         (Modified)

Status codes:

• M = Modified
• A = Added
• D = Deleted
• R = Renamed
• C = Copied

Viewing Commit Differences

To see which commits are in one branch but not the other:

# Commits in feature-branch not in main
git log main..feature-branch

# Show one-line format
git log --oneline main..feature-branch

# Output:
# abc123 Add user authentication
# def456 Fix validation bug
# ghi789 Update documentation

This shows commits that will be merged when you merge feature-branch into main.

Two-Dot vs Three-Dot Syntax

Git offers two comparison modes:

Two dots (..) - Show total differences:

# Show all differences between branches
git diff main..feature-branch

# Equivalent to:
git diff main feature-branch

Three dots (...) - Show changes since divergence:

# Show only what changed in feature-branch since it diverged from main
git diff main...feature-branch

# This excludes changes made to main after the branch point

The three-dot syntax is useful for seeing what your branch actually changed, ignoring updates to main.

Comparing Branches Visually

For a graphical view of branch differences:

# Show commit graph
git log --graph --oneline --all main feature-branch

# Output shows branching structure:
# * abc123 (feature-branch) Add authentication
# * def456 Fix bug
# | * ghi789 (main) Update config
# |/
# * jkl012 Common ancestor

This visualizes where branches diverged and their respective commits.

Finding Which Branch Contains What

To see if a branch has certain changes:

# Check if feature-branch has commits from main
git log feature-branch..main

# If empty output, feature-branch is up to date
# If shows commits, feature-branch is behind

# Check if main has commits from feature-branch
git log main..feature-branch

# Shows what's in feature-branch but not in main

Comparing Specific Files

To see differences in specific files between branches:

# Compare specific file
git diff main feature-branch -- src/app.js

# Compare multiple files
git diff main feature-branch -- src/app.js src/auth.js

# Compare directory
git diff main feature-branch -- src/

Showing Statistics

To see how much changed:

# Show change statistics
git diff --stat main feature-branch

# Output:
#  src/app.js         | 25 ++++++++++++++++------
#  src/auth.js        | 45 +++++++++++++++++++++++++++++++++++++
#  tests/auth.test.js | 32 ++++++++++++++++++++++++++
#  README.md          |  8 +++++--
#  4 files changed, 102 insertions(+), 12 deletions(-)

This shows files changed and line counts.

Comparing with Remote Branches

To compare your branch with remote branches:

# Compare local main with remote main
git diff main origin/main

# Compare local feature with remote main
git diff origin/main feature-branch

# Compare two remote branches
git diff origin/main origin/feature-branch

Make sure to fetch first to get latest remote changes:

git fetch --all
git diff origin/main origin/develop

Finding Merge Base

To find where two branches diverged:

# Find common ancestor
git merge-base main feature-branch

# Output:
# jkl012abc...

# Show what changed since divergence
git diff $(git merge-base main feature-branch)..feature-branch

This shows exactly what your branch added since branching off.

Comparing Across Time

To see how branches evolved:

# Compare main now vs main yesterday
git diff main@{yesterday} main

# Compare feature-branch 1 week ago vs now
git diff feature-branch@{1.week.ago} feature-branch

# Compare at specific date
git diff main@{2024-01-15} main

Ignoring Whitespace Changes

To ignore whitespace when comparing:

# Ignore all whitespace
git diff -w main feature-branch

# Ignore whitespace at line ends
git diff --ignore-space-at-eol main feature-branch

# Ignore whitespace changes
git diff --ignore-space-change main feature-branch

Useful when comparing code with different formatting.

Showing Function Context

To see which functions were changed:

# Show function names in diff
git diff --function-context main feature-branch

# Or use -W
git diff -W main feature-branch

This shows the entire function that was modified, providing better context.

Comparing Binary Files

For binary files, show which changed:

# Show that binary files differ
git diff --binary main feature-branch

# List binary files that changed
git diff --numstat main feature-branch | grep -E "^-.*-"

Exporting Differences

To save differences to a file:

# Export to patch file
git diff main feature-branch > changes.patch

# Apply patch later
git apply changes.patch

# Export as formatted patch
git format-patch main..feature-branch

Interactive Diff

For a more interactive comparison:

# Use difftool for visual diff
git difftool main feature-branch

# Configure difftool (one time setup)
git config --global diff.tool meld
git config --global difftool.prompt false

Popular diff tools: meld, kdiff3, vimdiff, Beyond Compare.

Checking for Conflicts Before Merge

To see if branches will conflict:

# Try merge without committing
git merge --no-commit --no-ff feature-branch

# Check for conflicts
git status

# Abort the merge
git merge --abort

Comparing Multiple Branches

To compare several branches:

# Show commits unique to each branch
git log --oneline --graph --all --decorate

# Compare branch A with B and C
git log --oneline branchA ^branchB ^branchC

Practical Comparison Workflows

Before merging feature branch:

# See what will be merged
git diff --stat main feature-branch

# Review commits
git log --oneline main..feature-branch

# Check for conflicts
git diff main...feature-branch

Comparing releases:

# Changes between v1.0 and v2.0
git diff v1.0..v2.0 --stat

# List changed files
git diff --name-only v1.0 v2.0

# Detailed changes
git log v1.0..v2.0

Syncing feature branch with main:

# See what's new in main
git log feature-branch..main

# See what you'll lose if you rebase
git log main..feature-branch

# Check divergence
git log --graph --oneline main feature-branch

Using Aliases for Common Comparisons

Create shortcuts for frequent comparisons:

# Add to ~/.gitconfig
[alias]
  compare = diff --stat
  cfiles = diff --name-only
  clog = log --oneline

# Use them
git compare main feature-branch
git cfiles main feature-branch

Best Practices

Always fetch before comparing with remote:

# Update remote refs
git fetch --all

# Then compare
git diff origin/main feature-branch

Use the right comparison for your need:

# File changes: git diff
git diff main feature-branch

# Commit list: git log
git log main..feature-branch

# Just filenames: --name-only
git diff --name-only main feature-branch

Compare from the right perspective:

# What's in feature not in main
git diff main..feature-branch

# What's in main not in feature
git diff feature-branch..main

Check both directions before merging:

# What you're adding
git diff main..feature-branch

# What you're missing from main
git diff feature-branch..main

Now you know how to see differences between Git branches. Use git diff for file changes, git log for commits, and the appropriate flags for the level of detail you need. Understanding these comparisons helps you review changes before merging and understand branch relationships.