Scattering Vs Diffraction

In simple words, scattering occurs when light hits a surface and reflects off it ... Therefore scattereing of light makes an object visible to you....

On the other hand, diffraction is bending of light around sharp edges or slits.
Diffraction is a phenomenon observed only in waves, but scattering is a phenomenon observed in both waves and particles.
Diffraction is a property of propagation of waves, whereas scattering is a property of wave interactions. 
Diffraction can be taken as evidence for the wave nature of light. Some forms of scattering can be taken as evidence for the particle nature of light.
These two are different phenomena. The phenomenon of splitting of light into its 'component colours' is dispersion. When white light is dispersed into seven colours by a prism, different colours of light bend through different angles with respect to incident ray. Out of these seven colours red light bends the least while violet light bends the most. 

When a ray of light is incident on extremely small particles, the particles 'deflect the light in different directions'. This phenomenon is scattering of light. The scattering of light take place through the atmosphere as the atmosphere is a homogenous mixture of minute particles like dust, smoke, tiny water droplets and moleculses of air. When the sunlight passes through a canopy of dense forest, scattering of light in the atmosphere can be observed. In the visible range of light, blue light scatters the most and red light scatters the least.r
Both are cause by the interaction of waves interact with objects. Diffraction is what you get when waves interfere with each other to produce some sort of pattern. 

Scattering is what happens when a wave or particle is kicked off in some direction. The term "scattering" is most often applied when the results of the interaction produce results that go off in all directions.

Both are really caused by the same underlying physical principles, but under different circumstances that give rise to emergent properties that are studied separately.