Hi @ohkay2, Here's an article/reference that explains the difference.

"Recent data suggest the need to distinguish between naturally occurring folates and folic acid (FA), terms often mistaken and used interchangeably, both by practitioners and consumers, causing considerable confusion.1
In particular, 5-Methyltetrahydrofolate [methylfolate, 5-MTHF, or (6S)-5-MTHF], has been evaluated as a better alternative to folic-acid supplementation.2-5 In this article, I endeavor to clearly identify the difference between folic acid and folate, pointing out why Quatrefolic, the 5-MTHF glucosamine salt from Gnosis by Lesaffre, is the ideal choice, suitable for anyone but in particular for those expressing methylenetetrahydrofolatereductase (MTHFR) polymorphism, which is approximately 40% of the global population.6-10"
-- Active Folate Versus Folic Acid: The Role of 5-MTHF (Methylfolate) in Human Health
https://pmc.ncbi.nlm.nih.gov/articles/PMC9380836/