Diffrence between timing and spacing ?

Lets take the eg of a bouncing ball the frames where the ball is hitting the ground is timing and the frames in between are the spacing of that scene.An object has to go from point a to b in one sec in a 24fps scene frame 1 and 24 will be timing how you gone reach from 1 to 24 is spacing you gonna fav the 1st frame or the last or you want slow in slow out or slow in fast out etc.

you will change the timing of the scene if you change the actual occurring of it say now the scene will end on 35th frame.And you will change the spacing of the scene when you will change the drawings in between for eg in bouncing ball your drawings are closer to each other at the top when its going from bottom to top you change that and it will give a diff result though its hitting the ground at the same time.

Both these things are pretty much the whole sole of the scene a lot of people say animation is all about timing and spacing.