Variables Creation and Usage Reports Package vs Tools Option

Summary:

We are currently investigating how we can make use of Variables in our Reporting Packages to make our reports dynamic. However, it seems there are two ways to manage these variables, but we only see use out of one method. What is the purpose of "Manage Variable Lists" in the Tools Options?

Content (please ensure you mask any confidential information):

We are seeing two ways to create and manage Variables. One, where we can go to the hamburger menu then Tools > Variables, and then the other within the Report Package itself. We understand the use from the Report Package. What is the use of the former? Any clarification would be greatly appreciated.