Using groups is the default method of managing multiple users in Jira; however, there are some limitations with using groups. The first limitation is that groups are global in Jira. This means that if a user is in a group, then that user is included in all projects in that group.

In real life, this is often not the case—for example, suppose a user is a manager in a project. He/she may not be a manager in a different project. This becomes a problem when it comes to configuring permissions and notifications.

The second limitation is that group memberships are controlled by the Jira administrator or central IT administrator if using LDAP. This means that using groups alone to control access to the project means that it is not managed by the project owners, and can result in a bottleneck.

So, to address these limitations, Jira provides us with project roles. Project roles are similar to groups; the only difference is that the membership of a project role is defined at the project level.