There's so much mis-information in this thread, I can't be arsed quoting everyone but that VGC article which says Spider-Man is just a 'remaster' is click-bait. If you read the quotes, there is nothing to be found on that front.
You didn't play Infamous:First Light, Uncharted Lost Legacy and said, oh these games are only remasters, these are standalone DLCs leveraging the previous tech. Same thing is with Spider-Man Miles Morales, but the difference being, they are building it around PS5, the lighting and texture in itself is a dead giveaway that, it is running on updated engine. Wait for DF to do their analysis, Sonys' shitty 1080p stream didn't do a good job of highlighting the details in many of the trailers.
At the moment it's not even confirmed how many PS4 titles will play on PS5. Sony said they want most of them playing but they didn't say when. They said that most of the top 100 games will play at launch IIRC.
On the topic of R*, GTAV on Xbox One X plays the same as the standard version. So don't expect them to bother updating RDR2
This is the type of stuff I was talking about. I don't blame the poster, sites like GiantBomb are still running with only 100 PS4 games will be BC. And, much of that is Sony messing up the messaging initially.
The PS5 SoC has 2 dedicated BC modes to mimic PS4 logic, one is legacy mode, the other is pro mode. So, the PS5, can disable 9WGP (18CUs), downlock to 800 MHz to mimic PS4, or downclock to 911MHz to mimic PS4 Pro. So, imagine, if you boot a game like Driveclub on PS5, a game which didn't get any Pro patch, the SoC will view the code like PS4 and disable 9WGP and downclock to 800MHz to run it as it ran on PS4, same for a game like Uncharted 4, it got a Pro patch, so, it'll downclock to 911MHz and play like it did on a Pro.
^It is different from boost mode, which is designed to leverage the PS5 clocks to boost the performance.
This is what Cerny was talking about when he spoke of Top 100 game thing, that in order to leverage PS5 clocks, they have to evaluate the code on game-by-game basis, the code which can't run on those speeds would need to patched by the devs.
Therefore, when sites like GB are writing about BC and Top 100 games, what they are actually talking about is
Enhanced BC. The basic BC is built in the SoC itself, as it can mimic the logic of predecessors. So, save for select few from thousands of PS4 games. Expect all of them to work on PS5, just don't expect all of them to leverage the PS5 clocks. That would require more work from Sony and devs.