how do we use "笑一笑，看一看“，and "看看”，what is the differences?

There's no difference
Structure
- one syllable verb: AA or A一A
看看，试试，听听，看一看，说一说，问一问
- two-syllable verb: ABAB
讨论讨论，学习学习，运动运动

Reduplication of verbs is used as an expression of a short time, a small amount, a light level or the act of trying something, with a rather gentle, comfortable nuance.

"见见面，听听歌，笑一笑，看一看”这些用法都一样吗？ 回答：用法都一样。只是语气比较轻而已。

There's no difference