A Canonical Name or CNAME record is a type of DNS record that maps an alias name to a true or canonical domain name. CNAME records are typically used to map a subdomain such as www or mail to the domain hosting that subdomain’s content.https://support.google.com/a/answer/112037?hl=en#zippy=%2Cset-up-cname-records-now
vs a record
An A record maps a domain name to the IP address (Version 4) of the computer hosting the domain. An A record uses a domain name to find the IP address of a computer connected to the internethttps://support.dnsimple.com/articles/a-record/
the difference, in a nutshell, being, cname normally is an alias mapping to a single server. while A record should map to a list of servers, which could be load balanced.