I have 3 ground planes that are each using physics shapes in a different way. The first has a plane physics shape, the second has a mesh physics shape with the unity standard plane assigned and the last one is segmented into 4 plane physics shapes. For each plane I have two balls with the same initial velocity, one has a sphere physics shape and one has a mesh physics shape with the standard sphere assigned. The setup of ground planes and spheres. The different physics shapes visualised (I highlighted 2 of the 4 segments so it's obvious it's built out of segments). With this setup some of the balls make small bumps with the ground plane in the case of the 'mesh' and the segmented ground plane, putting them slightly into the air. Besides that the mesh sphere collision ball seems to have a completely different simulation in comparison to the sphere collision ball. Beneath you can see a top-down screenshot of the different positions the balls are in after a few seconds. To reiterate, the left ball on each plane is the mesh physics shape while the right one is a sphere physics shape.