Final answer:
Archaea and bacteria are both prokaryotes, but they differ in DNA, biochemistry, and cellular structures. Archaea can thrive in extreme environments, while bacteria have a broader range of habitat preferences.
Step-by-step explanation:
The key difference between archaea and bacteria is that archaea are prokaryotic while bacteria are also prokaryotic but differ in their DNA and biochemistry. Archaea have distinct cell walls and plasma membranes compared to bacteria, and their ribosomal proteins are more similar to those in eukaryotic cells. Additionally, archaea can live in extreme environments, while bacteria can live in a wider range of conditions.