Well, it could be because they've had 6+ months to figure out what to do about one, and just a few weeks for the other.
Facebook knew about the Cambridge Analytica data harvesting way back in 2015. The true extent of it was only exposed to the public on March 2018 because a CA whistleblower[1] talked to news outlets about it.
Therefore, Facebook had ~2 years before the negative stories were blasted everywhere.
Because, as we all know, Facebook only really starts trying to figure out how to solve a problem once it becomes a scandal.