In Japan, へ ranks first, followed by に, へ is the father and に is the son.

Born earlier, they are often written in classical Chinese, so they are often used in written language, which is more solemn, and also used in formal occasions, such as writing where to go by plane (Tokyo) and who to send a letter to (Kenichi). Because these occasions need solemnity, generally we can't use に instead of へ.

にに is a modern Japanese, which appears in spoken English with a soft tone and can be used in general occasions. For example, when talking with friends, you usually use に instead of へ. Although へ can be used, it gives people the impression that you are too serious.