I don't have a document, but I sell/support both. To me, Sage 100's superiority always boils down to these three big things:
Customization: Sage 50 allows a limited number of custom fields and only on lists, not transactions, really, while Sage 100's can be at the transaction level and can be passed through to other tables.
Integration: Sage 50's integration has no data verification and fails easily, sometimes half-way done.
Robust GL, including divisions: Sage 50 lets you define GL account segments but doesn't go much beyond that, and has no posting by division as Sage 100 does.
Minor things: Sage 100 is concurrent licensing
Sage 50 is crash prone
Sage 50 slows when it gets full
Sage 50 has to be put in single user mode to carry out many tasks, whereas Sage 100 allows you to keep working in one module while closing another, for instance.
Sage 100 works well in a T/S environment