Is there any difference in usage or meaning? or are those exactly same?
"Children" is more formal than "kids".
Both terms can be used to refer to humans who have not reached adulthood. "Kids" is sometimes used informally for adult humans whose behavior is immature, such as college students who drink too much.
When speaking about family relationships, someone's "kids" or "children" are their sons, daughters, or other people they raised from a very early age. So an old man's children might "have grown up and had kids of their own."
"Kids" has other meanings, such as goats that have not reached adulthood. "Children"'s meaning is specifically for humans, or in stories where animals are acting like humans.
American legal documents often use the term "children", but rarely use the term "kids". Depending on the context, "children" can mean humans under the age of eighteen years, or can mean natural and legally adopted sons and daughters.