Is there a hierarchy to stories in agile projects

In my projects I often have a story (some work that can be done in an iteration) and an epic (something that will take more than an iteration).

I then break my stories into

• User story (As a user I want to do something so I gain some benefit)
• Performance cards (the system will be able to do something by iteration sometime) and
• Experiments (we want to know something so we will do something and measure something).

But I think I am out of step with the rest of the agile world.  I am told there is now more of a hierarchy that goes like this …

Does that look right to people?