The films were Kodacolor, Kodacolor X, Kodacolor II, Kodacolor III in that family. Now it is the Gold family I guess.
There was also Ektacolor S and Ektacolor L for professionals and that eventually merged into the Portra and Ektar family.
The improvements were in speed and grain along with sharpness. Color reproduction was kept rather similar in all of them since C41 was introduced. For example, Ektar 25 was the best we could do in the 90s for grain and sharpness, but today the same Ektar name is on a 100 speed film with better grain and sharpness. It also keeps better. These are the major areas of improvement in just one film family, to give an example.
Engineers from Fuji could say much the same about their products.
And, the choice of making positives at the cape was by making an Ektacolor original and then print it onto Ektacolor print film for a superb tonal range. Direct positives were made using Anscochrome, but they gave muted colors.
At that time, Agfa, Fuji and most other companies made unmasked color negative films which gave inferior color.
An example of positives from negatives are shown in the missile pictures in my gallery. They are rejects so they are not quite as good as the approved prints.