A: In the Toulmin model, the statement that explains how the evidence supports the main idea is called the backing.
A news report is typically an objective account of events, the purpose being to INFORM a reader about a subject or event. a persuasive paper is a more personal piece that would probably have examples including oneself (i.e. using the word "I") and its purpose would be to PERSUADE, or guide a reader into a certain logic.
your language would change from objective, meaning no "absolute language" (such as always or never), to persuasive. in a persuasive paper, using absolutes is a common tactic to get someone to believe something. you would also include more of yourself and you'd be trying to sway the reader, while the news report would be straight forward.