What are the differences between Subversion and Git?

Directory structure

Each reference, or labeled snapshot of a commit, in a project is organized within specific subdirectories, such as trunk, branches, and tags. For example, an SVN project with two features under development might look like this:

  sample_project/trunk/README.md
  sample_project/trunk/lib/widget.rb
  sample_project/branches/new_feature/README.md
  sample_project/branches/new_feature/lib/widget.rb
  sample_project/branches/another_new_feature/README.md
  sample_project/branches/another_new_feature/lib/widget.rb

An SVN workflow looks like this:

• The trunk directory represents the latest stable release of a project.
• Active feature work is developed within subdirectories under branches.
• When a feature is finished, the feature directory is merged into trunk and removed.

Git projects are also stored within a single directory. However, Git obscures the details of its references by storing them in a special .git directory. For example, a Git project with two features under development might look like this:

  sample_project/.git
  sample_project/README.md
  sample_project/lib/widget.rb

A Git workflow looks like this:

• A Git repository stores the full history of all of its branches and tags within the .git directory.
• The latest stable release is contained within the master branch.
• Active feature work is developed in separate branches.
• When a feature is finished, the feature branch is merged into master and deleted.

Unlike SVN, with Git the directory structure remains the same, but the contents of the files change based on your branch.

Including subprojects

A subproject is a project that's developed and managed somewhere outside of your main project. You typically import a subproject to add some functionality to your project without needing to maintain the code yourself. Whenever the subproject is updated, you can synchronize it with your project to ensure that everything is up-to-date.

In SVN, a subproject is called an SVN external. In Git, it's called a Git submodule. Although conceptually similar, Git submodules are not kept up-to-date automatically; you must explicitly ask for a new version to be brought into your project.

Here are some external resources that explain the differences in more detail:

• Understanding Git Submodules
• Git Tools Submodules

Preserving history

SVN is configured to assume that the history of a project never changes. Git allows you to modify previous commits and changes using tools like git rebase.

Further reading

• "Subversion properties supported by GitHub"
• "Branching and Merging" from the Git SCM book
• "Importing source code to GitHub"
• "Source code migration tools"