How to determine 2 objects at same space collision

Hi. I want to determine if two moving objects in 3D occupy the exact same space (such as on a 3D grid). I am trying to use the 3D collider and rigidbody, but this may not be the correct solution as the colliders are not exact and the objects are moving. Thanks for any help.

Have you tried the polygon collider on physic instead rigidbody? To have an exact 3D object with same parameters try to duplicate same object.