Did you see any difference in the pictures? I would suspect that they are synonyms... yellow by another name. But I would be glad to stand corrected if there actually is a difference.
I just visited your site and I am in awe! WOW! So many great things. Not just the plants. Your growing areas and injinuity (spelling) and creativity. Absolutely awesome!
While I agree with Roberta that “aureum” and “flavum” are used synonymously, technically they mean “golden yellow” and ”yellow”, so I supposed there is an intended difference.
Botanical taxonomists for the most part no longer use the concept of variety. The label used would be subspecies. Flower color isn't normally used in deciding what defines a taxon. Variety is a concept used by horticulturalists, more like a catalog description.
__________________ May the bridges I've burned light my way.