In GitHub Actions, environment variables can be defined at three different scopes: workflow, job, and step. Each scope determines the visibility and lifetime of the environment variable across the workflow execution.
Variables defined at the workflow scope are available to all jobs and steps within the workflow.
Variables defined at the job scope are available to all steps within a specific job.
Variables defined at the step scope are only available to the step in which they are defined. They are declared within a step and are not visible outside of that step.
Reference:
https://medium.com/@leroyleowdev/github-actions-ways-to-share-data-between-jobs-
4267ff9ac2ce