Hi.

What compounds are added while manufacturing wall paint that determine if results are glossy or flat finish ?

"The sheen^[4] or gloss level of a paint is principally determined by the ratio of resinous, adhesive binder, which solidifies after drying, and solid, powdery pigment. The more binder the coating contains, the more regular reflection will be made from its smooth surface; conversely, with less binder, grains of pigment become exposed to the surface, scattering the light and providing matte effect.^[5] To a lesser extent, gloss is also affected by other factors: refraction index of the pigment particles, viscosity and refraction index of the binder."

From Paint sheen - Wikipedia

And, of course, different manufacturers use different binders for the fairly standard pigments, depending on application.