1. Breathing: Whales breathe air through lungs, just like other mammals. They must surface regularly to take in oxygen. Fish, on the other hand, breathe underwater using gills.
2. Live Birth and Milk: Whales give birth to live young, and mothers nurse their offspring with milk. Fish lay eggs.
3. Warm-Blooded: Whales are warm-blooded, meaning they can regulate their own body temperature. Fish are cold-blooded and their body temperature fluctuates with the surrounding water.