Amorphous solids encompass a broad range, including glass, gels, silica gel, amorphous semiconductors, amorphous superconductors, amorphous carbon, and amorphous metal-metal alloys.
Glass is just one type of amorphous solid, specifically referring to substances that exhibit a glass transition during heating or cooling. The glass transition occurs when glass, or a melt heated to a point where it may form glass, cools to approximately two-thirds to one-half of its melting point (in absolute temperature), at which point its coefficient of thermal expansion and specific heat capacity change significantly. This phenomenon is a key characteristic that distinguishes glass from other amorphous solids such as gels and amorphous carbon.
