Hi
Sheffield has four routes:
Y, Yellow, from Middlewood to Meadowhall
B, Blue, from Malin Bridge to Halfway
P, Purple from Cathedral to Herdings Park
TT, no colour, Tram-Train from Cathedral to Parkgate
The trams display the letters on the relevant colour background next to the destination. The whole trams are not branded to a particular route, though the tram-trains are confined to certain sections.
Hope that is of interest.
And here is the network map...