I know they both put the gems in your app in different locations but it seems as if bundle install --deployment does a more thorough job. Can I just add the
I use bundle install --path vendor/bundle in development mode.
bundle install --deployment will lock yor Gemfile.lock and will not update it when you change your Gemfile, so never use deployment option on development environment.
bundle install --no-deployment will disable bundle deployment mode.
You can read that post about bundle usage in right way.