What is the difference between FreeNAS and FreeNAS?

I guess the question should actually should be "what is the difference between FreeNAS and TrueNAS", because now it says "between FreeNAS and TrueNAS. The answer to that question is, there is no difference. TrueNAS used to be called FreeNAS in the past.

Freenas had it's name updated to Trunas and received a ui update other than that its the same team and same product.

Well, as stated there is no difference between these. Meaning is it safe to assume you meant to state the difference between TrueNAS and FreeNAS. Functionally, I am not aware of much difference between these two either. Run them both today in production.

I assume to mean the difference between FreeNAS and TrueNAS. If so FreeNAS was the original project they had created TrueNAS as the commercial offshoot. Over time they retired FreeNAS and are only upgrading TrueNAS from now on.

There is no difference when comparing FreeNAS to itself...

I suspect this is comparison of the various editions in which case you can check here: https://www.truenas.com/compare-editions/

I think you mean FreeNAS and TrueNAS? The main difference is then merging the codebases of their open source and enterprise product so it's easier to develop and maintain. Going forward only TrueNAS will be getting updates.