Given requestBody is a JSON, does it matter if I run the above or below? does the fileType just change the extension of the file?

//var fileObj = file.create({name:fileName,fileType:file.Type.PLAINTEXT,contents:JSON.stringify(requestBody),folder:folderParameterValue});
      //var fileObj = file.create({name:fileName,fileType:file.Type.JSON,contents:JSON.strinfiy(requestBody),folder:folderParameterValue});
      //var fileId = fileObj.save();

Also, is there a reason why the code doesn't work in restlets? But it worked in the debugger...