Why is cooking a food item method called different things by what the item is, or what is the criteria?

On the Food network they boil potatoes, but they poach carrots. They poach turkey, but they boil eggs. They sauté' onions, but they fry eggs in the same pan. Likewise, they fry hash browns, but they sauté' onions in the same pan before adding the potatoes.

I can go on for days.