Difference between liferay hooks and Ext's

Hooks Plugins	Ext Plugins
Hook Plugins are used to customize or override the default behavior of liferay in the form of properties and jsp files.	Ext Plugins are used to customize and extend the Liferay Portal.i.e almost customize everything. Nothing but we can create new Root Web app.
Using Hooks we can override a).Event Handlers(Application startup events,Login events,Service Events). b).Language Bundles. c).Jsp files(either portal or portlet folder). d).Model Listners. e).Services.	Using Exts we can customize a).portal-impl as ext-portal-impl. b).portal-service as ext-portal-service. c).util-bridges as ext-portal-utilbridges.. d).util-java as ext-util-java. e).util-taglib as ext-taglib. f).web as ext-portal-web.
These are recommended way of extension and maintaince easy.	These are recommended when there is no way of implementing required functionality  using hooks.
Hot deployable	Not hot deployable and server must restart
Combine with other plugins like portlets.	These are some difficulty and customize almost everything.