Here's why:

* Crystalline materials have a highly ordered, repeating arrangement of atoms, molecules, or ions. Think of it like a perfectly arranged Lego structure.

* Amorphous materials lack this long-range order. Their particles are arranged more randomly, like sand.

Examples of crystalline materials:

* Salt (NaCl)

* Diamond (carbon)

* Quartz (SiO2)

* Metals (like gold, silver, copper)

Examples of amorphous materials:

* Glass

* Rubber

* Plastics

* Some types of ceramics