So if you are looking for unique content you should have one site for eash category. Two sites with the same subject is pretty much obvious they are going to have very similar content. The difference is the way that each site displays the content, and that's probably what you mean unique(?).
There are many different ways to have unique content. But all of them really boil down to the same thing.
Every website is PERSONAL. MY website represents what I have experienced and learned, what I have done, and will do (for money, or for the love of it). It can be unique because my person and my history are unique, and it will be unique if I use it to express the uniqueness in my person or history.
The same principle applies to artist sites--and fan sites, political and religious and ethnic sites, professionals' and amateurs' sites, church and school and charity and business sites.
It's all personal. It's always personal.
So what of you is expressed on your website? And I don't mean "you chose your favorite color for the background." I don't mean the website style at all. I mean the information contained on the website.
And ... can the reviewer find that personal expression? Or is it hidden behind all the things that the website wants "you" (i.e. the impersonal surfer) to do? Because the only "person" expressed on the website is one that wants to be paid for marketing effort?
Short rule of thumb. "I'm going to hell", "I've been to hell and it was bad", "Offering tours of hell for money" -- all unique, because nobody else knows that corner of hell like you do. "Go to hell and tell them I sent you, you will like it, there are all sorts of interesting experiences, and Satan is offering me referral fees" -- not unique.
Bad cess to all competitors. The websites worth listing have NO competitors.
Joes-plumbers.com is unique. It has no competitors. Joe may well have a dozen competitors in his neighborhood alone, not to mention plumbers who (for a sufficient fee) will drive from another city. But the WEBSITE has no competition because no other website on earth can tell exactly what Joe and his hirelings can do, and what they would do for money.
That's very simple, I think. Whether any particular person wants to create such a non-competitive site is another issue. There's no law saying anybody has to. Many people don't bother.
The ODP is looking for the ones who do care.