Is an object's center used to measure distance between them or is it its volume?

When checking for distance between objects, does it calculate from both of the object’s center, pivot, or their entire volume?

I’m not very clear on this.

Your question isn’t very clear either.

Using what code? What methods?

What are these “objects”? Transforms? Rigidbody?

What is it you actually want to achieve here?

Working on a racing game. I’m using box colliders as checkpoints along a track. I’d like to use a rigidBody’s (vehicle) transform to determine which racer is closest to the collider to determine who is the leader & so on.

I don’t understand how physics can help you solve this problem. Collider are used for resolving collisions or detecting if something overlaps an area, not for checking distances to target.