The English language nouns Movement and Motion have related meanings, but they are different, as I shall explain, using British English examples.
Motion implies changing position without intent. It describes the physical properties of moving. It is normally emphasising something is not stationary, rather than commenting on where it is going.
"The motion of the planets is determined by gravitational attraction."
"I started to feel sick because of the boat's rocking motion."
When something is In Motion, it is moving. Note, you can not say "in movement".
"Once the train was in motion, I started to read my book."
"I can't put my makeup on in the taxi when it is in motion."
Movement implies the qualities of moving. If a person is moving, they will almost always be using movement, not motion. If moving is deliberate, it is movement. Movement is also used when the important factor is going from one place to another, whereas motion is used to describe something not being still.
"The movement of the dancer was exquisite."
"There was a great movement of people between India and Pakistan in the 20th century."
While in many cases either movement or motion can be used, you should try to use the above guidelines to help you choose the right word to sound more natural in your use of the English language.
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