Ten links from one website count for less than ten links from ten different websites. Referring domains lists every site that links to you, ranked by its authority, so you can see which relationships carry the most weight.
The dofollow/nofollow split shows how many of those links pass authority to your site. Together they tell you where your strongest support comes from, and which kinds of sites to approach next.
Referring domains
Every website linking to you, ranked by authority