It’s usually close enough, and some data is accurate on daily basis - the usage updated from the satellites, however, since it’s accumulated information, it become a precise only for the day, but not for the entire month.
You may see this discrepancy if you would use Earnings calculator (Update 2023-12-05: v13.1.0 - Now with support for different payouts per satellite - Detailed earnings info and health status of your node, including vetting progress) for the previous periods.