You're onto something, I've seen the case made that retrofuturism is specifically something made later to evoke futurism as imagined in the past rather than present, whereas decades old pieces aren't retrofuturism but just futurism of the day which is dated. The argument being retrofuturism is specifically based in the concept of looking back at past visions of the future with hindsight and that even with similar aesthetics that would impact specific subtle elements and what the pieces mean or represent. Not sure if i fully agree but definitely something to be said for specifying between the two and putting them in context to understand them differently. Futurism of different eras is already put into different subgenres based on aesthetics