correction above! ..."used for emphasis in spoken English"..

There isn't a semantic difference between "everyone" or "everybody", but the word "everyone" sounds slightly more formal, and used more often in literary English. The same is true for "anyone" and "anybody", and "no one" and "no body". Also, the use of "no one" is used for emphasis as in spoken English as in, "No one in the city does that sort of thing!"

There are no differences between the words in each pair. (Spelling "no-one".) You can choose which one you like.