Whats the dofference between Query Parameter and body()(as request body) while hittign the Post request?

IN oauth Module, you are hitting a post request to create a new tweeet. we havn't used body() to pass the request bosy, Instead we have used QueryParameter().
I think QueryParameter is use to fetch the Result on few filter basis but this example totally changes the concept.
Can you please elaborate the difference b/w QueryPara,eters and Body?