Difference between ATF Type F and FA ?

[Jerry]

I picked up a few quarters here and there and noticed that the FA is quite a bit thinner at room temp although the specs at 100C are the same. I did see that the flashpoint for FA is 100F higher than F. Otherwise, any insight welcome. Only comments on FA marketing info is that it's supposed to help reduce slippage or older vehicles.
Thanks in advance. JR