Nice..

Oscillation and Vibration both are guided motions about a fixed point ,, commonly called mean position..

In oscillation the distance from the fixed point remains constant and its trajectory is commonly an arc of circle whose radius is "the distance of oscillator from point of oscillation",, like in simple pendulum!!

Consider such a motion(forget gravity, m talkin of trajectory); thenwhat if we make the distance from that point of oscillation zero. Means the particle will now be stationary, but if you take projection of this oscillation on a plane, the particle will appear to move to and fro about a point in fixed line,, what we call is vibration!!

I hope you got the difference..