Nobody other than Tesla knows why a gray "coming soon" pin shows up on Tesla's supercharger map. Many are there as coming soon for years (although perhaps the validity of those coming soon pins is evolving given Tesla is now suggesting that info could be updated quarterly for at least some of the pins). The supercharge.info data is all crowdsourced by people across the world that devote time to searching online records for permits (blue pins) or evidence a site is under construction through visits or other verifiable evidence. So the supercharge.info map will have fewer pins, but the data tends to be "real".
EDIT: I should add... thanks for posting these two maps side-by-side. It is interesting to contrast the two. And also really great to see the progress that has been made in the Northeast in the past year, with signs that 2021 will have lots of continued progress!