For me, the real crucial different between PbtA and FitD is that FitD tracks some mechanics for the entire group. In Blades, you have your terf and your heat, in Scum and Villainy, you have your ship. Meanwhile, PbtA only tracks mechanics personally. Sure, the town you're in may have some scarcities, but that really only matters for the people in charge and not for the wandering gunlugger. This means that FitD games tend to focus on intra-group dynamics to a degree that PbtA does not have to.