Complex sentence: The Network RUS is one of only two (the Freight RUS is the other) which have the perspective of the network as whole; most of NR's RUSs are geographical, mainly regional, in nature.
Split into simpler sentences: The Network RUS is one of only two (the Freight RUS is the other) which have the perspective of the network as whole. Most of the Network Rail's (NR) RUSs are geographical, mainly regional, in nature.