Contrast: The author shows less emotion. Just show the readers the difference between several things.
For example, Wang gave birth to a daughter and Zhang gave birth to a son.
Successful people are as few as sparrows in winter, and ordinary people are as many as stars.
Set-off: More emotional, you will obviously feel the author's tendency, or he just wants to express one thing.
For example, almost all the flowers bloomed overnight under the command of Wu Zetian, and only the peony proudly adhered to its flowering period (the obedience of other flowers was used to set off the nobility of peony. Although you didn't see the full text, you can feel that this is an article mainly about peony rather than flowers. In addition, it is easier to distinguish judgments if there are contextual prompts)