Final answer:
Betelgeuse and Aldebaran, both red giants, are immensely luminous due to their sizes, with Betelgeuse being exceptionally large and outshining our Sun, but they also have relatively lower surface temperatures indicated by their red color.
Step-by-step explanation:
Betelgeuse and Aldebaran are both notable examples of red giant stars, recognized for their significant luminosity and relatively cooler surface temperatures. The cooler temperature of these stars is manifested through their red color, a distinguishing characteristic of red giants. Red giants like Betelgeuse have enormous size, and Betelgeuse particularly is so large that it can extend outwards as far as Jupiter's orbit, dwarfing a main-sequence star like our Sun by comparison.
In assessments of luminosity and temperature, Betelgeuse is extremely luminous, often thousands of times more so than our Sun, primarily due to its size, while its surface temperature is lower, giving it that characteristic reddish hue. A direct comparative analysis between Aldebaran and Betelgeuse regarding luminosity and temperature specifics would involve their position on the Hertzsprung-Russell diagram, which illustrates differences based on spectral type and magnitude.