I will leave two videos down below since Dr. Ekberg explains it much better than I ever could, but basically table sugar and high fructose corn syrup differ in that the latter has a higher concentration of fructose in comparison to glucose. Table sugar is 50% glucose, 50% fructose, whereas HFCS always will have more fructose than glucose although the actual percentage can vary. The aim behind creating HFCS was because researchers realized fructose doesn't affect blood sugar levels as much as glucose, but now we know that is because fructose can only be metabolized and digested by the liver, therefore, HFCS nowadays is one of the culprits causing non alcoholic fatty liver disease.

Is this a gimmick?

Real sugar tastes and is better!