It's a bit like football rivalry.
For example, Tottenham fans absolutely hate Arsenal, because Arsenal are local and more successful. But because Arsenal fans know Arsenal are so much better than Tottenham, they merely have a patronising dislike towards Tottenham, and instead hate Man Utd and Chelsea more.
Hence, UWE tend to have a slight issue with Bristol students, whereas Bristol students aren't massively fussed, and instead prefer to laugh about how Warwick looks like a ****ing Center Parks.