I might just add a few comments to the previous answer. Having lived in Panama for many years, I can give you some changes on the southern end of Central America (although sometimes, Panama is sometimes referred to separately from Central America because it used to be part of Colombia.). Niños and niñas are only used until the age of 5 or 6; then they use the word muchacho or muchacha which can also be used for teenagers although jovenes is used more commonly. There is also the word chico or chica. All of these words are probably well understood throughout the Spanish speaking world. A word like "cool" is considered slang even in English, and the same holds true in Spanish. The word divertida (fun) is probably also understood in most countries. Some more slang words for "cool" in Panama are priti (pretty), cul (cool), and chevere. As you can see, the Panamanians like to play around and adopt English words, but pronounce them with a Spanish accent. Spanish probably varies more from one country to another with slang than with many other words.
