The MX record specifies the hostname of the computer or computers that process emails for a domain, as well as a priority code. Emails are forwarded to the host's IP address, which is specified in the A-record.
Domain: copernica.com is an example of an MX record.
mail.copernica.com is a mail exchanger.
Priority number ten
The A-record (also known as the address-record) indicates which IP address is associated with a domain name. The domain name is 'translated' into an IP address via this record.
An A-record example:
copernica.com is the domain name for the website Copernica.com.
mail is the name of the host.
11.22.33.222 is the IP address.