Application server provides Hot deployment when it re-deploys modified JSPs.

It is necessary to recompile .jsp file and place new .class file to a proper class folder to achieve Hot deployment.

Servlet container provides Hot deployment when it re-deploys modified servlets and JavaBeans.

You cannot change only a part of a web application.
In order to modify some core components like JSP/servlets/EJB
it is necessary to undeploy the whole application and deploy the new compiled version.

Hot deployment is the process of adding new components
(EJBs, servlets, and JSP files) on-the-fly without stopping the application

Dynamic reloading is the ability to automatically detect servlet/JSP/EJB source change,
recompile and reload any web component on-the-fly.

When application server detects a new servlet or JSP

Dynamic reloading is the ability to change an existing component like JSP/servlets/EJB without restarting the server
In the case of JSP, the change will be automatically detected and the JSP will be recompiled and reloaded