localhost with 127.0.0.1

Domain Name
A domain name is the name of a computer or group of computers on the Internet that identifies the computer's electronic location when data is transmitted.
A domain name is a string of dot-separated names, usually including the organization name, and always includes a two- to three-letter suffix to indicate the type of organization or the country or region in which the domain is located.

DNS Domain Name Server
DNS (Domain Name Server) is a server that converts domain names and corresponding IP addresses.
DNS stores a table of domain names and corresponding IP addresses to resolve the domain names of messages.
The domain name server stores the domain names and corresponding IP addresses of all hosts in the network, and has the function of converting domain names into IP addresses.
The domain name must correspond to an IP address, a domain name can have multiple IP addresses, and an IP address does not necessarily have a domain name.

Local Domain Name Server
DNS is a computer's Domain Name System (Domain Name Service), which consists of domain name resolvers and domain name servers.
DNS resolution process and principle

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localhost with 127.0.0.1
localhost:
Local server
Not transmitted via NIC
Not affected by network firewall and NIClimits.

127.0.0.1:
Local address (local server)
Transmission via network card, network card dependent
Restricted by network firewall and network card

localhost is preferred for local services when setting the program. localhost will not be resolved to IP and will not occupy network cards and network resources.When using localhost to access, the system brings the permissions of the current user of the machine to access; and when using ip, it is equivalent to accessing the machine through the network.