Confusion on Metadata | Named Forks | Extended Attributes | Resource Fork -- HFS+
Confusion arises from the fact that the relationship between these concepts is complex and has changed over time. In current systems the difference between a named fork and an extended attribute is largely academic. 

For an extended attribute, the actual data is stored in the attribute data record. 

For a fork, what's stored is the list of disk allocation blocks that contain the data. A resource fork is still a fork. 

Basic file system metadata is stored in dedicated elements of the file system record itself, independent of the attributes and named fork references.