Elliptical galaxies are characterized by several properties that make them distinct from other classes of galaxy. The motion of stars in elliptical galaxies is predominately radial, unlike the disks of spiral galaxies, which are dominated by rotation.
Furthermore, there is very little interstellar matter (neither gas nor dust), which results in low rates of star formation, few open cluster, and few young stars; rather elliptical galaxies are dominated by old stellar populations, giving them red colours. ….
The properties of elliptical galaxies and the bulges of disk galaxies are similar, suggesting that they are formed by the same physical processes, although this remains controversial.