No, there is a difference between a "romcom" and a classic film. A romcom is the new, ultimate conventionalization of what used to be a light love story. There were many great examples of this. But it is now been so watered down and assembly-line manufactured that it is meaningless drivel.
A classic film is absolutely different. It exists in NO CATEGORY. It is simply a great film of any kind. Truffaut and Goddard and other great filmmakers deliberately avoided these mindless conventionalizations. What they did isn't simply another interchangeable category as you cynically suggest.
Also, I am so tired of people saying "filmmaking is storytelling." It is ANYTHING the filmmaker wants it to be - including pure abstraction, avant garde animation, documentary realism, anti-storytelling, ANYTHING. It is NOT merely storytelling even if the increasingly idiotic "industry" conceives of it that way.