Corn syrup and high-fructose corn syrup are two different ingredients, although they share some words. One is 100% glucose and the other also contains fructose (usually 42% or 55% fructose), produced by chemically altering the corn syrup. We process glucose and sucrose differently and it affects taste, satiation, digestion, and more. I agree that the terminology is useless, by institutional intention.

> chemically altering the corn syrup.

And where does corn syrup come from? From squeezing corn? The sugars in corn don’t start as glucose either (they’re starches).

Besides, at home, bakers easily make “HFCS” themselves by adding any weak acid to table sugar to make invert sugar (an HFCS 50 equivalent).

> We process glucose and sucrose differently

Tell that to some southerners about their sweet tea. This simple distinction isn’t that metabolically interesting for day to day life (or explaining the prevalence of obesity and metabolic syndromes). Concentrations in a serving and mode of delivery are far more important. You can pretty easily get metabolic syndrome from excess glucose as well as sucrose. Altering smell and moisture content are more impactful variables.

Sucrose readily hydrolyzes to glucose and fructose via sucrase in the small intestine, it and HFCS become equals (no, Mexican coke isn’t healthier you dumb hipsters, just eat a piece of fruit already). If it wasn’t you’d get massive diarrhea from eating it. So sucrose vs HFCS isn’t nearly as distinct.

> and it affects taste, satiation, digestion, and more.

The most important distinctions go beyond the relative concentrations of the simple sugars. A fresh fruit doesn’t have the same insulin spiking and metabolic syndrome inducing potential as plain Karo syrup or a (Mexican) Coke, even though its relative percentage of fructose is higher or similar.