In JIRA, we have three levels of hierarchy: Projects -> Issues -> Sub-Tasks. If you want to push it, you can also include Project Categories. I found this basic hierarchy to be insufficient to represent a Work Breakdown Structure (WBS) and in this post we'll explore the possibilities at your disposal.
In JIRA, the term "Project" suggests you should use JIRA "Projects" to represent your own projects. However this is not always the best decision, because of the other elements associated with JIRA Projects, namely Versions and Components (not to mention any Configuration). Most of the larger organizations I've worked with use JIRA "Projects" to represent the different products or applications they work on. But what about actual projects?
With the JIRA Agile add-on, we add a new element to the basic JIRA hierarchy: Epics. In Agile, epics represent large deliverables that usually take longer than one Sprint to deliver. Epics are eventually broken down into Stories, which are also broken down into Sub-Tasks.
So now we have: Projects -> Epics -> Stories (issues) -> Sub-Tasks. This is definitely an improvement, but if you're using JIRA Projects to represent a product or an application, you still have nothing in JIRA to represent your actual projects.
One of the most important aspects of JIRA Portfolio is the fact it adds a new element to the JIRA Structure: Initiatives. Initiatives allow you to group epics into higher-level projects. In fact, I believe Initiatives should be called Projects, but as we all know, the word is already used by JIRA.
If you're using JIRA Portfolio, you can make a clear distinction between your products / applications, and the actual projects your working on. With all these dimensions and levels at our disposal, we can (finally!) build a WBS directly in JIRA (Portfolio!)
Do not hesitate to contact us if you're looking for a demonstration of JIRA Portfolio, we'll be glad to do one for you.