The update panel performs a complete re-rendering of the page, occupies the section corresponding to the panel, and sends it to the client. Then the browser replaces the contents of the update panel with a new html.
jQuery The AJAX method allows you to make any request to any page and process the response data in any way. This may include reading a JSON response from a web service, receiving html, or anything else you wish. Effectively, AJAX provides you with a mechanism for emulating a user viewing a given URL with GET or POST data and managing the results anyway.
It is worth noting that the update panel is built on top of AJAX (technically Javascript XMLHttpRequest ).
There are also some fixes with the update panel, for example, if you have a Captcha that is outside the panel; When the panel is updated, the visibility captured by the user does not change. The server creates a new page, including new code. When a user submits a form, their verification code is for the old code.
In short, you have more control with AJAX, and learning how to use it will be useful, but depending on your use case, the update panel may do what you need for less effort.