After using Github for several years, I recently used Gitlab for a solo developer project.
Some of the differences I noticed over the past two weeks were:
1. After initial signup, I got a 422 error HTTP response for about 5 minutes. I assume my new login was propagating to their caching layer(s). See screenshot below.
2. By default, the master branch on repos is “protected” and a maintainer must remove that for regular users to push to.
3. Gitlab markdown is different than Github’s.
4. No tagging of repos with the probable computer language. (seems to work for me as of Nov. 13, 2018.)
5. When sharing a private project, the “Guest” role cannot view source code.
I hope this helps programmers transitioning from Github to Gitlab. Please leave a comment below if you encounter other differences.