How do you know that the type of the rock is the only difference between tombstones?

The type of rock used for tombstones can differ in durability, appearance, and symbolism, which can influence their longevity and aesthetic appeal. However, other factors such as design, carving techniques, and inscriptions also play significant roles in distinguishing tombstones. If a comparison focuses solely on the type of rock, it may overlook these other important elements that contribute to the uniqueness of each tombstone. Thus, while rock type is a key difference, it is not the only one.