Final answer:
Spiral galaxies feature extensive star formation, young stars, interstellar matter, and a rotational internal motion, while elliptical galaxies consist mostly of old stars, exhibit little to no star formation, and have random internal star movements. Spirals are disc-shaped with spiral arms, and ellipticals are ellipsoid in appearance. The evolution and mass-to-light ratio of these galaxy types also differ significantly.
Step-by-step explanation:
The main differences between spiral galaxies and elliptical galaxies concern their shape, color, content of gas and dust, star formation activity, internal motion, and texture. Spiral galaxies, such as our Milky Way, typically feature a flat disk with a central bulge and spiral arms winding outwards. These galaxies are often characterized by their vibrant blue color due to the presence of young, hot stars, especially in the spiral arms. They contain large amounts of interstellar gas and dust, which is conducive to ongoing star formation. The internal motion within spiral galaxies tends to display rotational patterns around the central bulge. On the other hand, elliptical galaxies are shaped like ellipsoids (ranging from nearly spherical to elongated), and they exhibit a smooth, almost featureless appearance. They are generally redder in color, indicative of older stellar populations, with very little or no ongoing star formation. Moreover, they contain little to no interstellar gas and dust. The stars within elliptical galaxies move on random orbits, leading to less structured internal motion compared to spiral galaxies. Additionally, the mass-to-light ratio tends to be smaller in spiral galaxies due to regions with prolific star formation, while elliptical galaxies, which lack new star production, exhibit a higher mass-to-light ratio. The evolutionary paths of these galaxies also differ, with spirals having undergone more complex and longer star formation processes, and ellipticals having formed most of their stars in a rapid collapse billions of years ago.