Two things generally separate them ---
Motion Pictures is another way to say "movie", and they usually involve "real life" people and things. They are longer than cartoons -- usually anywhere from an hour to two hours.
Cartoons are animation -- they are not real people or things. They are drawings or pictures of things that are put into movement. They are usually short and seen on tv. 30 minutes or sometimes an hour long.
Now, there are sometimes cartoons that are longer and are shown in a movie theater. These are rare. But these rare cartoons seen in a movie theater we will also call motion picture. But then usually there will be some explanation that it is a cartoon, and not a "real life" movie.
I hope this helps.
Cheers from China!!