A freighter was a kind of vehicle, often a spacecraft.
The XV class was a class of space-faring freighter that was not built for warp drive. The kidnappers of Romulus and Remus Sylvest modified the freighter XV773 to accommodate a warp drive. (TV: The Twin Dilemma)
LIZ 79, Milo Clancey's spaceship, was a C-class freighter. (TV: The Space Pirates)