* Cows have four-chambered stomachs (rumen, reticulum, omasum, abomasum) as part of their digestive system for breaking down tough plant matter. This is because they are ruminants, meaning they chew their cud and digest food in stages.
* Whales are not ruminants. They have a single-chambered stomach, which is very large and complex, allowing them to digest large quantities of krill, fish, or other prey.
While both whales and cows have large digestive systems that can hold a lot of food, their internal structures and digestive processes are quite different.