You may find that some VPNs have physical servers in certain countries, while others have virtual servers.
Physical servers are physically located in the country. So, for example, NordVPN's Turkey server is a bank of servers located within Turkey.
A virtual server has an IP address registered in the country, but is actually physically located somewhere else. ExpressVPN's Turkey server, for example, is actually in the Netherlands.
This is most common in countries that are anti-VPN, or areas where setting up a reliable server would be difficult or impossible. Often, virtual servers are more reliable than physical servers in the same country, as they rely on the infrastructure of a country with better internet service or more stringent privacy laws.