The sugar in milk is lactose (glucose + galactose). Soda is basically fructose and glucose. So the glucose if common between the two.

I want recommendations of "don't eat sugar" to dig into the details, because sugar is everywhere. My mother-in-law "doesn't eat sugar" but constantly snacks on figs/dates, pours honey over everything, and drinks fruit smoothies daily. In my opinion, she has a very high sugar diet despite not adding any table sugar or corn syrup to anything. Many recommendations say to limit "added sugar" without explaining why naturally occurring sugar is okay.