What affects the scale of target velocity to Revolute joints to move at a particular speed?

I have two different models,
Model A has 2 controlled revolute joints, Model B has just 1 controlled revolute joints. All revolute joints are used to make the robots move.
Model A moves at x m/s if I set the joints target velocity as x/r (r is radius of wheel).
I expected same behavior for Model B, But model B needs much much higher joint target velocity to make the robot move at desired speed, for 1 m/s I have to set the joint target velocity as 452.48 units. This does stay consistent, like its a multiplying factor.
Seems like mass does not affect it.
Where does that multiplying factor come from and how do we change it?
Thank you!

Is it possible that the joint drives for Model A are lacking strength to achieve the target velocities? (e.g. the proportional gain is too low?) Or perhaps they have a max force that is preventing them from achieving the proper effort. What is the joint drive type - Force or Acceleration?

If you could share those details about the joints, that would be helpful.