I was trying to understand the difference between these two things, manifest.js and config.assets.precompile in application.rb

When we want to use some specific CSS or js for a page, we usually add that into the config.assets.precompile and include that JS/CSS in the page using (javascript_include_tag or stylesheet_link_tag). If we wanted to use any CSS or js at the global level, then we are adding under the application.js or application.css

Recently I have seen manifest.js, so instead of adding the files under config.assets.precompile, add that in the manifest.js and include it in the specific page where we need that. So what would be the difference? Which one can we use it?