$.ajaxPrefilter() Vs $.ajaxSetup() - jQuery Ajax

Question

While learning through ajax in jQuery, I came across 2 terms, viz., $.ajaxPrefilter() and $.ajaxSetup(). All I can find out is that these

Answer 1

$.ajaxSetup() - Set default values for future Ajax requests. You could, for example, set the ajax URL that you always want to use for every request here.

Example:

$.ajaxSetup({
  // Always use this URL for every request
  url: "http://example.com/ajax.php"
});

---

$.ajaxPrefilter() - Modify existing options before each request is sent. You could, for example, append a query string component to every ajax request that is sent out.

Example:

$.ajaxPrefilter( function(options) {
    // Always add "?debug=1" to every URL
    options.url += (options.url.indexOf("?") < 0 ? : "?" : "&") + "debug=1";
});