I don't think it's been said explicitly, but my understanding it's about the stories of 4th and 5th Symphony being under the general banner of Symphony of the Sword. Given the timeskip that takes Kate & Utena from being still at High School to a year or so into college, there's an arguement that this should be under a separate overall title and organised somewhat differently

That's what I got from reading the thread, anyway. I could have the wrong end of the stick.