| Feature | Merge | Rebase |
| What it does | Integrates changes from one branch into another by creating a new merge commit that records the union of both histories. | Moves the entire set of commits from your branch and reapplies them on top of another branch (usually the main one). |
| Effect on commit history | Preserves true historical timeline. You can see when and how two branches diverged and then merged. | Rewrites history by changing the base of your branch, as if the commits were made sequentially on top of the target branch. |
| Structure of history | Creates a non-linear history that shows the full branching structure and context of collaboration. | Creates a linear history that appears clean and ordered but loses details of when branches actually diverged. |
| How it affects commits | Keeps all existing commit hashes unchanged and adds one new commit (the merge commit). | Changes commit hashes, dates, and potentially the order of commits, because commits are recreated during rebase. |
| Context preservation | Preserves full historical context, including how and why branches were developed separately. | Loses the branching context — the rebased history looks like it happened in a straight line, regardless of the actual timeline. |
| Commit graph appearance | You'll see branches merging back together with clear visual splits and merges in tools like Git log or GitKraken. | You'll see a single line of commits with no sign that a separate branch ever existed. |
| Typical usage scenario | Used when integrating completed features or hotfixes back into main branches like main or develop. | Used when you want to clean up or prepare your feature branch before merging or submitting a PR. |
| Team collaboration | Preferred in teams where multiple people work on the same branch — merge preserves everyone’s work cleanly. | Risky in shared branches — if you rebase after pushing, it creates problems for teammates pulling your changes. |
| Conflict resolution | Conflicts (if any) occur once at the merge point, and the resolved state is committed with a merge commit. | Conflicts can happen at each commit being rebased, requiring step-by-step conflict resolution. |
| Use on shared branches? | Safe and encouraged. Maintains stable collaboration and conflict resolution workflow. | Not safe after pushing to shared branches. Should only be done locally before pushing to avoid disrupting others. |
| Undo capability | Easy to revert using git revert -m 1 <merge-commit> or by resetting to a previous known commit. | Harder to undo if pushed — rebased commits differ from original, making rollback complex. |
| Does it rewrite history? | No. It simply adds to the existing commit graph. | Yes. It literally changes commit history by creating new versions of existing commits. |
| Best used when | You want to maintain full visibility of parallel development paths. | You want a streamlined, clean history that appears as if all changes happened in sequence. |
| Impact on Git log | Git log shows all merges and branches, giving you full traceability of how work was done. | Git log shows a linear stream of commits, hiding how work was divided across branches. |
| Impact on Pull/Merge Requests | Merge commits provide clear indicators of when a PR was integrated and allow for easier PR traceability. | Rebased branches appear as if they were part of main all along — PR merge points disappear. |
| Command used | git merge <branch> | git rebase <branch> |
| Risk of error | Low. Merge is a conservative operation that doesn’t change past history. | Medium to High. Rebase can be dangerous if misunderstood, especially when used after pushing. |
| Fast-forward behavior | If no other changes exist, Git will fast-forward the branch pointer without creating a merge commit (unless using --no-ff). | Rebase achieves a fast-forward-like effect by restructuring commits ahead of time. |
| How Git views them internally | A merge is a new commit with two or more parents. | A rebase is a replay of commits, as if they were written from scratch on a new base. |
| Common in open-source projects? | Yes. Many projects prefer merge to maintain an auditable history of PRs. | Sometimes used in PR cleanups, but usually done before opening a PR, not after. |
| Effect on history integrity | Maintains a complete and truthful project history, ideal for auditing and debugging. | Creates a linear but rewritten history, good for small teams or solo developers. |
| Golden rule | Use merge for shared work, and when preserving historical collaboration matters. | Use rebase for cleaning up local work, and when preparing for clean integration. |