[GIS] difference between Simple and Attributed relationship classes

Question

In the esri geodatabase, what is the difference between Simple and Attributed relationship classes?

Answer 1

Slightly edited snippet from a conversation in the GDAL/OGR Mailing list:

Relationship Classes come in two types

1.- Simple Relationship Classes
2.- Attributed Relationship Classes

Conceptually, they just relate one (or more) column(s) in one field to another column(s) in another table. Besides also including cardinality information, and enforcing referential integrity (when the underlying db doesn't support it), they are used inside ArcGIS for display and editing purposes. The fact that the may or may not have domains associated with them is orthogonal to this discussion.

For the first kind (simple), they only exist in metadata tables - they don't map to any physical tables on the db.

For the second kind (attributed), they do refer to actual non-spatial tables on the db.