So I know this has been discussed before in regards to some the Apps daylilies, but suddenly this year, I am seeing this Rainbow Rhythm trademark with a large handful of known daylilies. It is a line being marketed by Proven Winners.

So my question is, is there a difference between Primal Scream being sold at various places versus the Rainbow Rhythm Primal Scream being sold via retailers that deal with Proven Winners?

Rainbow Rhythm is a trademark of Walters Gardens. The actual cultivar name should be written with single quotes but a lot of sellers don't necessarily follow the rules of nomenclature which makes things confusing. In other words you should be able to tell the proper cultivar name by the way it is written, i.e. Hemerocallis RAINBOW RHYTHM (R) 'Primal Scream', meaning that the actual cultivar name is 'Primal Scream'. A trade designation is not a recognized name. Unless there are two 'Primal Scream' in circulation it should be the registered one, otherwise the name would be written 'Rainbow Rhythm Primal Scream', all in single quotes.