Ships don't define a faction, but rather what the ships do. Many touted the G1A to be a "Scum B-wing", but it's so much more than that, despite it's on-paper stats and dial. Heck, even the Scum Z95 plays in a vastly different manner to the Rebel version, merely through the inclusion of an illicit slot. The pilots, too, have defined and refined the Scum faction, and given it a character through the abuse of dirty tricks and ruthless combos. If ever there was a testament to that, it's the Hwk; a ship that people are pushing through the voting process for the System Open finals as a handicap for Rebel players, but which is widely regarded as a strong support ship for Scum, all due to it's pilots.
Ships are just things. It's the pilots that define them, and they in turn, the faction.