Kind of hard to say given the structure of it. Going off the approximate data from FediDB's charts, we may be looking at around 2 to 3 million more user accounts (around 8 million to 7.25 million), as compared with data from Stats for Bluesky of 5.24 million.

Although I'm not sure how each is measuring this, a better point of comparison may be active users and daily posters. FediDB uses the former, and shows about 940,000 to 920,000 active users, compared to Bluesky's about 220,000215,000 to 190195,000 daily posters. The latter is honestly being kind of generous, as going off the data there posting has been declining. Interestingly liking has stayed somewhat higher, hovering between 240,000 to occasional peaks of 260,000 recently.

According to their CEO just before they opened registrations they had 1.6 million monthly users, so maybe if you run the numbers differently it looks better...But the raw stats don't paint a great picture, at least as I read them.

Going off Join Mastodon's servers page (under network health), we see a figure of 942,000 monthly active users, which would suggest Bluesky should arguably have slightly more activity going off the monthly active users figure, but... 🤷‍♀️