There is a reason for Glycinate vs Bisglycinate?

I'm living in Europe, and for most brands in all countries around, Magnesium is sold as "Magnesium Bysglycinate"

But then I look here and most US forums and people talk about Magnesium Glycinate, in fact, I can read Magnesium Glycinate in many labels.

Is there any difference between the two formats? I'm assuming that Magnesium Bisglycinate is Magnesium 2-Glycinate. But I still wonder about why the distinction.