Doesn't it sound very similar? However, there are trucks of differences between these two friends. A glance over a few aspects would help us get a better view of the contradiction.
GitHub-A software development and distributed version control host; it offers the provision in source code management, whereas GitLab is a DevOps lifecycle tool(now Agile as well) which yields Git repository manager for issue tracking and continuous pipelining. Both Gitlab and GitHub collaborate on code and also offer a simple issue tracker that enable status and assignee change for various issues.

Most of us are aware that GitHub public repositories are freely available to a vast audience(of course developers)-an open-source software. The recent release by GitHub gives you a provision of integrated CI/CD tool to automate the tests and buckle up the development process. Tracking comment changes, navigation towards method/function in a changed file and triggering the pipeline are few of the exceptional features of GitHub.
Though GitHub makes a continuous effort to prove itself, the amenities that Gitlab provides, made a shout-out right from its birth.

The key endorsements of Gitlab that won the hearts of developers over GitHub include the following:

• The Share Runners allow the usage of Gitlab CI/CD for free up to 2000 build minutes for private and unlimited for public projects.
• You can import into, export projects and issues from various sources such as Bitbucket, GitHub, google code, etc. and self-learn with the documentation and guides.
• Project issues, Milestones and Iterations can be carefully scrutinized in sync with your Agile project development.
• Gitlab is now available for the Agile operations; the highlighting features like Environment Auto-stop, single integrated tool, value stream analytics and self-monitoring would switch the excitement mode on if you're a developer.
• If you're struggling with feedback, fixture and preview changes, Gitlab's Web IDE helps you stay in touch with your client Merge request and Gitlab CI.