Supergiants are massive stars that are in the later stages of their life cycle. They have extremely high surface temperatures, ranging from 10,000 to 50,000 Kelvin. This is due to their immense size and the intense nuclear fusion reactions occurring within their cores.

White dwarfs are the dense remnants of stars like our Sun. They are much smaller than supergiants and have exhausted their nuclear fuel. They have relatively low surface temperatures, typically ranging from 4,000 to 40,000 Kelvin.

Therefore, supergiants have significantly higher average surface temperatures than white dwarfs.