Epics, Themes, User stories and Tasks are all these are records and new terminologies are part of scrum and the differences between these are very clear to deliver the stories to stakeholders in any agile/scrum projects.
The prerequisite to create the themes, epics and user stories is to create a product even before and we should attach these records mandatory with the defined product to submit to the further phases.
Broadly the highest level of story and describes an area of focus.
A Large work, which contains stories as a huge requirements which are not rationalized.
This is a simplest story what user actually wants, which are smallest unit of work.
Here scrum user breakdown the stories into multiple tasks, which are discreet bits of work require to complete a story
It is a iteration where team does the work in the specific period of time of 2 weeks to 4 weeks
“EPIC” are group of big user stories. We can simply place all the highest level stories together and call the whole thing as EPIC, and these epics are at broadest level which will describes mainly an area of focus.
The term “Theme” simply stands for a big user story broken down into a number of smaller stories. There is no exact limit to when user stories become Themes. A Theme can span more than one project, if multiple projects are included in the board to which the Theme belongs.
“User Stories” describe what users want. Although they are more than a few words on a file card, for our purposes it is sufficient if we think of them as a simple text. If we think of user stories, they should be individual requirements which are small enough to estimate. A common acronym for comprehending the characteristics of user stories is that they ought to be as “INVEST”: Independent, Negotiable, Valuable, Estimable, Small, and Testable.
SAMPLE DIAGRAM WITH EXAMPLE:
As elaborated above that EPICS are bit larger than THEME stories, THEMES are larger stories, and User stories are smallest units.