Reflection is the phenomenon of Light by which it bounces back, uniformly, from a SMOOTH surface.
Refraction is the phenomenon by which light changes it path (by bending) while passing from one medium to another.
Dispersion is the splitting of white light into its 7 constituent colours upon getting bounced with certain special conditions (Angle, Medium etc).
Light ray scatters when it gets bounced, unevenly, from a ROUGH surface.
I'll expain it if u want to knw it deeper.