The white ones are originally from silkworm producers that have gone feral over the years, silk worms don't like the native black mulberrys, and they are sweeter, too sweet for me.
I find that to be true for the white ones also.
White Mulberries used to be very rare here.
Up until 5-6 yrs ago i had only seen three in prob 60 yrs..
Now like the black ones they are more common here.
The one thing with Mulberries is the berry is constructed a lot like a grape cluster.
Little stems to each lobe of the berry.
Doesn't bother me any but i've heard complaints.
Find you a fist full of the ripe ones and you will probably reach for more.
None of the trees in my area produced this year, ( late frost issue I think.)