A domain is something which replaces an IP address which is more user friendly. For an example, in a web browser you probably type something along the lines of "atomichost.xyz", This here is a domain. This domain then goes through a server, which then translates it to the servers IP Address, because the IP Address shows the content of our website, this is also displayed on the domain.

So a domain is a user friendly way to navigate through places across the internet, instead of memorising an IP Address. e.g. 192.168.0.1

A DNS Record (Domain Name Server Record) is a way to tell the service you are getting your domain from, what IP address that domain will link to. you have many records like, A, AAAA, SRV, TXT, CNAME and many more, but we will be focusing on A, AAAA and SRV Records