I caution you against applying too rigid a hierarchy to these terms.  We tried to do that in my previous job.  Twice.  Both attempts were different and both times we found we had unnecessarily limited ourselves.  The only constant was the definition of a User Story.  From a planning perspective, a story is the basic building block of a project.  The larger terms (epic, feature, etc.) are effectively just tags.  Tags are an easy way to allow a story to exist as part of multiple Epics and multiple Features at the same time.  It's not worth the mental effort to be more strict than that.

Tags work for Stack Exchange and they can work for you too.

Relationship between user story, feature, and epic?
[using salt --version: 2015.5.0] I want to add a rule that allows ALL TRAFFIC from another security group 

I have this in my pillar: 

securitygroups:
    groups:
       - name: NFS
         region: us-east-1
         vpc_id: vpc-1234
         description: desc
         rules:
           - ip_protocol: -1
             from_port: -1
             to_port: -1
             ec2_group: sg123456


API suggests to use -1 to specify all IpProtcol. But I'm getting this error:

----------
          ID: secgroups_NFSecurityGroup
    Function: boto_secgroup.present
        Name: NFSecurityGroup
      Result: False
     Comment: An exception occurred in this state: Traceback (most recent call last):
                File "/usr/lib/python2.6/site-packages/salt/state.py", line 1563, in call
                  **cdata['kwargs'])
                File "/usr/lib/python2.6/site-packages/salt/states/boto_secgroup.py", line 140, in present
                  _ret = _rules_present(name, rules, vpc_id, region, key, keyid, profile)
                File "/usr/lib/python2.6/site-packages/salt/states/boto_secgroup.py", line 345, in _rules_present
                  to_delete, to_create = _get_rule_changes(rules, sg['rules'])
                File "/usr/lib/python2.6/site-packages/salt/states/boto_secgroup.py", line 265, in _get_rule_changes
                  raise SaltInvocationError(msg.format(ip_protocol))
              SaltInvocationError: Invalid ip_protocol traffic specified in security group rule.
     Started: 03:09:58.163808
    Duration: 235.323 ms


from_port: -1 and to_port: -1 works fine if I specify an ip_protocol: icmp|tcp|udp
