Durham and Notts as places, are pretty different and so with unis that academically are sl close as others have said, the only way to decide is to go to both of the them, use ure vibes and look at the place, Notts is a campus whereas Durham is spread out, but Notts is a proper city whereas Durham is still a city but definitely on a much smaller scale.
Durham has more hills i'd say lol. if it comes down to it, which prospectus and website do you prefer, ring switchboard who sounds nicer, little "meaningless" things like that may help you decide who uni feels more like you and you'd be happier at. you've got to live there for 3yrs don't forget, so you don't want to be stuck somewhere you don't especially like both are great unis don't worry about that side of it, forget league tables and the like now, who gives you better food on the visit days haha, it could be a sign they value their students more and want you lol.
Simply focus on the aesthetics of each places.
Don't worry if it makes you seem vain, one of these will be YOUR uni, you want to feel proud of it, you wouldn't buy a house without even seeing a picture of it lol, and noone really wants to buy a house they find ugly.