cross link between own sites

Google says it is OK to cross link between ones own pages, but not too much. Most dont do it, is there a difference in that and 301 redirects with empty domains? Does it consider as same as linking between sites? If the domain is close but not same? What if when there are many empty 301 domains...

Google says it is OK to cross link between ones own pages, but not too much. Most dont do it, is there a difference in that and 301 redirects with empty domains? Does it consider as same as linking between sites? If the domain is close but not same? What if when there are many empty 301 domains...