Glass is generally more fragile than porcelain. This is due to the differences in their compositions and structures. Glass is a non-crystalline amorphous solid, meaning it lacks a regular, repeating pattern of atoms. This amorphous structure makes glass more susceptible to cracking and breaking under stress. Porcelain, on the other hand, is a type of ceramic that has been fired at a high temperature, resulting in a dense, hard, and brittle material. While porcelain is also brittle, its high density and strength make it less likely to break than glass when subjected to the same forces.

Data from the American Ceramic Society indicates that porcelain has a higher compressive strength than glass. For instance, porcelain can withstand compressive forces of up to 20,000 psi, while glass typically has a compressive strength of around 10,000 psi. This difference in compressive strength is a significant factor in determining the fragility of each material. Additionally, porcelain's higher thermal shock resistance allows it to withstand rapid temperature changes without cracking, whereas glass is more prone to thermal shock and subsequent breakage.

The molecular structure of glass also contributes to its fragility. Glass is composed of a network of interconnected atoms, but these bonds are not as strong as those in porcelain. When stress is applied to glass, the weak bonds can easily break, leading to cracking and shattering. Porcelain, with its stronger atomic bonds and denser structure, is better able to withstand such stresses without fracturing.

In summary, glass is more fragile than porcelain due to its amorphous structure, lower compressive strength, and weaker molecular bonds. These factors make glass more susceptible to breaking and cracking under stress, while porcelain's denser and stronger composition provides greater resistance to damage.