Man United v. Liverpool is not a Derby. It is just a regional rivalry. Man United's Derby is against Man City. Liverpool's, is against Everton. As someone else said, the United Liverpool rivalry is a big deal for the two sets of fans, rather than being seen as a major match in English football. read more
Derby is a match played between clubs of the same city. As Liverpool and Manchester united both belong to different cities, they cannot have a derby match. Manchester united and Manchester city make Manchester derby whereas Liverpool and Everton make Merseyside derby. read more