Both are considered \”fresh\” or unripened cheeses. Both are usually sold in the same type of round plastic container. They can be used in many recipes interchangeably, but there are some distinct differences.
Ricotta is a soft cheese that has a fine, moist, grainy texture. Cottage cheese is \”lumpier\”, whether the curds are small or large.
Cream is added to the curds to create the rich \”creamed cottage cheese\” we are all familiar with. For low-fat cottage cheese, 1% or 2% milk replaces the cream. A half cup of creamed cottage cheese contains about 115 calories, while 1% cottage cheese has about 80 calories.
A half cup of ricotta cheese made with whole milk contains about 215 calories, while ricotta made partly with skim milk has only 170 calories per half cup.
Some savory recipes such as lasagna or stuffed shells will accommodate either cheese. However, because of the extra liquid in cottage cheese, the end result will be runnier than if you use the drier ricotta.
On the other hand, substituting one for the other in a dessert in which texture is crucial (such as cheesecake) can be problematic, unless the recipe specifies otherwise.
In the Test Kitchen, we have had some luck processing cottage cheese in the blender to get a smoother product, but this works best in dips and recipes that can accommodate the extra moisture.
So even though the two cheeses can be used interchangeably in some recipes, the recipe itself often dictates which is the better choice.