I once inherited a tool stack with extra backing pieces nobody had drawn. Looking at our new UR5e proposals feels familiar: both suppliers quote the housing mass, neither includes the long fingers, adapter or hose fittings in the comparison. I can't choose a tool without knowing what the complete assembly asks of the wrist.
Ask for the full assembled mass and centre of gravity with the housing held, plus the geometry and intended motion for the supplier's load assessment; the housing weight alone leaves out most of what you're comparing