periodic motion is a motion of body wich repeats itself in equal intervals of time , but a oscillatory motion is a periodic motion which is about a mean position . so all periodic motions could not be a oscillatory motion , but all oscillatory motions are periodic in nature.

To-and-fro motion of an object about a fixed point is known as Oscillatory motion.

vibratory means stationary with no motion, oscillatory means with uniform motion like pendulam.

In vibratory motion, the body doesn't move as a whole.where as in oscillatory motion the body moves on whole .and in vibratory motion the amplitude is less ,where as in the oscillatory motion the amplitude is comparitively larger than the vibratory motion .

yes, all oscillatory motions are periodic but all periodic motions are not oscillatory.