Difference between "Fan Of The Past" and "We Will All Be History Buffs In The Future"?

I suppose Fan of the Past could also apply to history buffs living in the present, or even those in the past who were fans of the more distant past, except the trope description and examples seem to fall under the same purview as We Will All Be History Buffs in the Future.

Or is there just something I'm missing?

Fan of the Past is about a single character who doesn't have to be correct about the facts. It's about references to our culture.

We Will All Be History Buffs in the Future is about everyone. While it can be about references to our culture, it's more about their own history for the purpose of exposition, so that we can know what's happened in their world, often in our future but their past.