An Rdataset is a set of Rdata objects which all have the same rdatatype, rdataclass, and covered type. Rdatasets also have a ttl (DNS time-to-live) field. Rdatasets support the normal Python set API, but are also ordered.
An RRset is a subclass of Rdataset that also has an owner name, i.e. a dns.name.Name that says where in the DNS tree this set is located.
A Node is a set of Rdataset objects, the Rdatasets being interpreted as at the same place (i.e. same owner name) int the DNS tree. Nodes are primarily used in Zone objects.
dns.rdataset.Rdataset
dns.rrset.RRset
dns.node.Node