link relation types
Link relation types is how IANA refers to existing rel values or the microformats rel registry, likely due to the IANA registry table of the same name: http://www.iana.org/assignments/link-relations/link-relations.xml#link-relations-1.
Link types is how HTML4 listed the various values for the HTML4 <a> and <link> element
rel attribute: http://www.w3.org/TR/html4/types.html#h-6.12. These have been incorporated into the formats table at the top of existing rel values.