[NTG-context] the difference between \def and \define

In plain TeX, we always use \def for creating a new macro, but in ConTeXt, sometimes it won't work, especially when making own chapter titles. The \def can produce the error message like this : "Argument of \... has an extra }". \define in ConTeXt can solve this problem. What's the difference between \def and \define? Can I use \define to replace all \def?