A colleague asked me the above question yesterday. A quick response:
Motivation is a result of energy you choose to switch on inside yourself. No one can motivate anyone else - that would usurp natural laws of will. What we call great motivators or leaders are people who inspire others to press their own internal switches.
You inspire others while inspiring yourself. For perfect balance, inspiration is a shared ritual.
Inspiration comes before motivation. Creativity is inspiration or intuition. All three words describe the activity of the third brain within you.
The left brain and right brain are the other well-known tags used in popular psychology. To explain InnerSpace Science practices, I use three aspects of the human brain, as a working metaphor.
That was my first response quite brief that inspiration comes from the creative side of the brain, whereas motivation is an act of willpower.
Inspiration may come involuntarily whereas willpower is a choice.