What is the difference between HTTP server and HTTPS considering my structure?

Question

I have a js Rest Node application running behind a proxy Reverse by Nginx, with https properly configured, where the server is configured as follows: Obs: app is my router.

const httpServer = http.createServer(app);
httpServer.listen(port, () => {
      console.log('hello');
});

And Nginx as proxy Reverse is set up as follows:

server {
    server_name example.com example.com.br;

    if ($host !~* example\.com$) {
        return 301 $scheme://example.com$request_uri;
    }

    location / {
    proxy_pass http://localhost:3003;
        proxy_buffering off;
        proxy_set_header Host $host;
    }

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/example.com.br/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/example.com.br/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}

server {
    if ($host = example.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = example.com.br) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    listen 80;
    listen [::]:80;
    server_name example.com example.virturian.com.br;
    return 404; # managed by Certbot
}

i can access the application quietly, everything is working perfectly, my question is, it is still necessary, considering a production environment, configure the express server as follows?

const httpsServer = https.createServer(credentials, app);
httpsServer.listen(port, () => {
  console.log('hello');
});

What is the difference between the two approaches, it is really necessary to already run https by Nginx, implement as httpsServer? Another question, I need to listen at door 443 with the second approach, or any other?