PHP FPM and PHP CLI - What handles Artisan Commands?

I'm curious to know if the Artisan commands are handled by PHP-CLI OR PHP-FPM. The context of the question is this -

I'm required to run an Artisan command every few seconds. Now my CRON won't go sub-minutes; and therefore I'm thinking of using a loop with sleep(x) -

foreach($items as $item) {
    sleep(15);
    Artisan::call('some-command');
}

I noticed that while this code executes, I can actually access various parts of my site without any delay; as if there is no connection between the execution of the above loop and browsing.

I concluded that Artisan command was handled by php-cli and my web requests were handled by fpm. Am I right?