В чем разница между kid и child ?Пожалуйста, приведите примеры.

Child is very slightly more formal and a little more babyish. The connotation when applied to someone who is not actually a child/kid is slightly different.

Calling someone who is significantly younger than you a kid is slightly patronizing but not necessarily insulting. Calling them a child would be insulting unless you have a parental relationship with them.

Saying an adult is acting like a kid is usually slightly positive and just means they're having fun the way a child might.

Saying an adult is acting like a child means they are being very immature and overly emotional and is a negative thing.

When used to refer to an actual child/kid they are pretty much interchangeable with no significant difference in meaning other than kid being slightly more informal.