Short answers, pulled from the story.
Huginn derives from a root word meaning thought, perception, comprehension, awareness, mood, sentiment, desire, or choice. Muninn stems from a root that encompasses affection, intent, will, care, urge, curiosity, interest, prediction, or memory.
The two ravens fly each day over the spacious earth known as Midgard before returning at dinner-time to keep Odin informed of many events. They sit on Odin's shoulders and tell him everything they see and hear while flying all over the world.
Migration Period gold bracteates from the fifth and sixth centuries feature a human figure above a horse holding a spear flanked by one or more often two birds. These artifacts suggest Odin and his ravens healing a horse rather than simply serving as battlefield companions.
Andreas Mogensen of Denmark and Marcus Wandt of Sweden flew under these names during their time in orbit aboard the International Space Station in January 2024. The pair was chosen to honor the ancient Norse mythological figures through this modern space exploration effort.
Scholars note these two terms were likely close synonyms with several shared and bordering senses rather than distinct opposites. The exact clear definitions behind these ancient names remain hard to extrapolate from surviving sources alone.