Froude’s law posits that gravity plays a greater force than friction compared to an object’s inertia as in Reynold’s.
An example of Froude’s law applied would be a ship sailing on water, whereas the force of gravity of the ship dispersed along its length acts much greater on it than the force of the viscosity of water on its trajectory.
Reynold’s number is typically examined in the context of Navier-Stokes. An examle of this would be a respirocyte in robotics or a colloid. Imagine a bead in a jar of honey- the force of viscosity, a special case of friction, is much greater the the force of gravity acting on the object.