No, the difference is larger.
The 825GB of the PS5 are "marketing" GB, which translates to 768 "real" GB.
The TerraByte are 1024 "real" GB, so the difference are 256 "real" GB between both
"real": 1KByte = 1024 Bytes
"marketing": 1KByte = 1000 Bytes. Marketing loves to use it for advertising the size of Harddiscs because it sounds more impressive. Some apps use it to make it easier for the users who do not know about the 1024 thing
The usage of the "marketing" GB was confirmed by Mark cerny around the time of his march talk, when he said something like that 825GB is the logical size because they are using 12 channels and 12 chips, and 12x64 = 825.
This has already been covered.
Not marketing but an IEC spec.
1 TB = 1000 GB = 1.000.000 MB = 1.000.000.000 KB
1 TiB = 1024 GiB = 1.048.576 MiB = 1.073.741.824 KiB
HDD/SSD vendors use TB/GB to define the size of their drives. Windows for example uses TiB/GiB, which is why a 1TB drive only shows 931GB within the windows file system. It displays as GB but is actually GiB.
So, the 1TB drive in an XBox One /S/X is 931GiB which is the size reflected in the OS. Same with the PS4.
Unless Microsoft are changing this in the Series S|X, the size reflected will be 931GiB for the X and 466GiB for the S.