Hi, bit late but I wanted to share my opinion because I've been studying at Preston for 2 years and I grew up in Burnley so I have quite a good impression of both places!
In my opinion, Burnley has some nice areas but I wouldn't recommend it for student life. The town is a bit of a dump if you haven't lived there your whole life - I like it because it's home to me but if I came as a new student I would hate it for sure. There isn't really a student atmosphere because UCLan shares it's building with Burnley College which is where I studied my A Levels and most people on campus are aged 16-18ish. Burnley UCLan doesn't have student halls so that's something to consider also. The nightlife isn't bad but Preston is far better.
Preston as a place isn't too different to Burnley. It's just bigger and the reason I think it's much better is because of its student atmosphere. Its buildings are spread around campus and there are so many options for accommodation. The many students definitely make Preston a lively city which I think Burnley lacks.
However, if you are commuting to Burnley or studying a part time course then the student atmopshere may not be something you're too bothered about. I'm sure the facilities at UCLan Burnley are great for some courses so definitely have a look round if you're interested. I just wouldn't recommend the Burnley campus if you're looking for a real student-y experience.
Hope this helped!
Molly