I'm assuming these are normal checksums (bitwise hashes), whereas before they were doing a hand-wavy AI-based thing that they called "checksums" but weren't really. The latter captured rough visual qualities of the images in question, which is why it had a false-positives problem. A real checksum shouldn't have that problem; in theory you'd only be able to detect an exact match of a file you already have and are looking for. So it is meaningfully different.
I assumed separate checksums are made from the file name and the contents. Though even if not, it would seem useful for eg. syncing between devices ("does file X already exist so we don't need to download it?")
Edit: confirmed that these are regular, real checksums https://support.apple.com/en-us/HT202303
> The raw byte checksums of the file content and the file name