An analogy compares two things. Usually one thing you know and understand, with something that is new or unfamiliar. When you compare the two, it helps you understand the new thing.
Esophagus / Water Slide
When thinking about digestion, the function of the esophagus can be compared to going down a waterslide and landing in a pool. The food slides down the esophagus tube and lands in the stomach.
Mouth / Garbage Disposal
When thinking about digestion, the function of the mouth can be compared to a garbage disposal. You scrap the food scraps into the sink, run the water and turn on the switch. The food gets chopped up into smaller pieces and goes down the drain.
Your teeth and tongue and salivary glands mash up the food just like a garbage disposal, and then you swallow the smaller pieces of food down your esophagus.
Stomach / Blender
When thinking about digestion, the function of the stomach can be compared to a blender. After putting different foods in the blender you close the lid and turn it on. It spins and breaks the food into even smaller pieces, it becomes a liquid. The stomach uses muscles to change the food pieces into liquid too.