Cook County Death Certificates from FamilySearch: Original or Derivative?

Recently, I made an interesting-to-me discovery that I thought would be worth sharing.
Below are two FamilySearch death index entries for the same person. The one on the left is from a collection (the term FamilySearch uses) titled Illinois, Cook County Deaths, 1878-1994. The one on the right is from Illinois Deaths and Stillbirths, 1916-1947.
Notice the differences. The index entry on the left has more information--address, cemetery name, and informant name, for example. And the birthplace is spelled "Pisek" on one and "Piseh" on the other.

Next let's look at the record retrieval information.
Notice there is no "GS Film number" for the record on the left. I believe this record set contains the images that were created by digitizing the paper certificates held by the Cook County Clerk's Office. I don't remember the year, but the project was done before I moved from Chicago three years ago. This index entry suggests the corresponding certificate can be purchased through cookcountygenealogy.com. (The link doesn't work because the URL has changed to https://genealogy.cookcountyclerk.com.)

The index entry on the right has a film number and a digital folder number. I believe the corresponding images (they are available, despite the "No image" note above) were created by scanning microfilm that was created years ago.

Now let's look carefully at the record sets that include the digital folder numbers. They can be found by going to Search > Catalog > Film/Fiche, typing in a folder number, hitting "enter," and clicking on the record set title.
It's a little bit hard to see, but the record set on the left was created from certificates held by the Cook County Clerk. This is a link to the genealogy page on their website and to the form needed to request death certificates from their Bureau of Vital Records by mail.
The one on the right was created from records held by "Public Board of Health Archives" (Illinois Department of Public Health) in Springfield. Here's a link to their genealogy page and to the form needed to request a death certificate from the Illinois Department of Public Health.

And finally, let's look at the corresponding records. The one directly below was found using information from the index entry on the left. This would be the record that's held by Cook County.

And the one below this is the one that was found using the index information on the right. This would be the record that's held in Springfield.

It looks to me as though the certificate held by Cook County is a derivative record, probably made by copying information from the original, perhaps by the by the submitter before it was sent to the county or by the county before it was sent to the state. And, it looks to me as though the certificate held by the Public Board of Health Archives is the original. I need to explore other records from other years to see if there is a consistent pattern, but I suspect that might be the case.
So, what does this mean for genealogists doing research in Chicago records? The short answer is -- it's a good reminder to look carefully at our sources and to seek out the best quality records possible.