All releases are tags, not all tags are releases. Have you used the feature?
> 1. On GitHub, navigate to the main page of the repository.
> 2. Under your repository name, click Releases.
> 3. Click Draft a new release.
https://help.github.com/articles/creating-releases/
Pushing a tag does not create a release. You can have lots of tags that are not releases. You have to choose to create a release, as a separate step. All your releases are tagged though, yes (as they should be, using github and it's release feature or not, to identify the state of the repo from which the release was built).
