The two terms are very closely linked. Even the Merriam Webster dictionary conflates the terms within it's definition of nostalgia: "a wistful desire to return in thought or in fact to a former time in one's life, to one's home or homeland, or to one's family and friends; a
sentimental yearning for the
happiness of a former place or time: a nostalgia for his college days."
But I think you are trying to make a distinction between personal nostalgia and nostalgia for a communal past that one did not directly experience; the difference between the sense of nostalgia I might feel watching a rerun of The Cosby show that I had previously seen, and the nostalgia I feel for a grand, imagined past that I get when I watch A Room With a View or read Anne of Gables or a Jane Austen Novel.
Now there is definitely something to that. We tend to view the past (as long as it is safely removed from us by a few decades ago) as charming, romantic, comfortable, even paradoxically 'familiar', even if we had never lived in that era. This is why fairy tale castles and '1940's Hollywood and Wild West saloons make for great theme park experiences. We love the idea of comfortabley stepping into the past.
Let's take a look at the Universal parks, and see what areas there evoke 'communal nostalgia', the nostalgia for a historical time gone by. Most of the lands in Islands of Adventure qualify: the Lost Continent gives us ancient Greece; Suess Landing gives us a fantastical non-history that certainly evokes a time other than our own, perhaps even the 1950's when most of Suess's books were published; Toon Lagoon has characters such as Popeye whose been around even longer than Disney's Snow White.
I would even argue that The Wizarding World of Harry Potter allows for communal nostalgia. True, the books are set in the 1990's. But the aesthetic of the Wizarding World are distinctly of the past. The architecture, claptrap, and even clothes range from Medieval to Victorian. Even if a visitor to the land had never seen a Harry Potter movie or read any of the books, they are effectively transported to a fictitious 'past', a place that evokes strong nostalgia.
Let's go back to your example of Seven Dwarfs Mine Train. True, it is a ride based on a piece of fiction that has stood the test of time and can rightly be termed a masterpiece. It is, after all, the film that started a completely new genre, the animated feature movie.
Now let's compare it to something Universal is currently working on: Potter Phase 2, featuring the Gringott's Coaster and Hogwarts Express. This franchise certainly has not been around for as long as Snow White. But I would argue that this I.P has firmly established itself as a modern day classic, and that it's legacy will reach about as long and far as other classic children's books.
So the real question here is, next year when, Diagon Alley opens up within months of the Seven Dwarfs Mine Coaster, what will be the greater draw? Nostalgia? Or nostalgia combined with substance and quality?
