Difference between Custom templates and Definition in Sharepoint

Custom templates here refers to Site/List templates while definition refers to Site/List definitions .Let me point out the key differences that helps us in our design decision ,

Templates -
Custom templates are created from the existing site /list through UI, that may or may not have contents .
Templates exists in the database .
Templates cannot be changed for further use and has to be used the way it is.
They are typically easy to create and deploy .

Definitions -
We create custom definitions by declaring the lists, fields, web features, site features ,content types ,navigation bars to be added with a site/list and registering them ,so that they can be used readily.
They exists in the web server (file system) ,hence better performance .
They can be customised and modified as & when required .
Not easy to create and deploy .
One has to have access to the Web server for deploying the definitons.