There are web applications that must always run on the server in order to work, create open port/socket we usually reverse proxy via Nginx or Apache later.
But there also are applications that do not run unless resource is requested or cron job is triggered. Most commonly PHP sites.
How can be call this two types to distinguish them?
Probably server-style versus CGI style? But it’s a blurry distinction because things we usually run as servers (such as node.js or rails) can hypothetically be run as CGI; and things we usually run CGI style (such as PHP) can also be run server-style with FastCGI.