How do giants stars differ from main sequences stars?

Giant stars differ from main sequence stars primarily in size, luminosity, and temperature. While main sequence stars fuse hydrogen into helium in their cores, giants have exhausted their hydrogen and are now fusing heavier elements, leading to increased brightness and larger radii. Additionally, giant stars often have cooler surface temperatures compared to main sequence stars of similar mass due to their expanded size. This results in a distinct position on the Hertzsprung-Russell diagram, where giants occupy the upper regions compared to the more centralized position of main sequence stars.