Both terms describe backend infrastructure your player connects to — here is what each one means for you as a subscriber.
IPTV server
The server is where the provider hosts the channel list, EPG data and streams themselves. When your player logs in with your username, password and server URL, it’s connecting to this server to pull that content.
IPTV portal
“Portal” usually refers to the same thing from a slightly different angle — particularly on MAG-style set-top boxes, which connect to a portal URL rather than a username/password login.
How this affects setup
Most consumer apps just need your Xtream Codes login or M3U link, and handle the server connection automatically behind the scenes — you rarely need to think about “the server” directly unless you’re using a MAG box.
If your provider changes servers
Providers occasionally move infrastructure for performance reasons. If your login stops working unexpectedly, check with support in case your server URL has changed.