There are many different kinds of refrigerators. They may differ by size, by outer design and by which method they use to produce low temperatures.
Domestic refrigerators and freezers for food storage are made in many different sizes from smallest that have volume of 4l to the large ones that can have up to 600l. They can also be combined with freezers or be without them. Those that have no freezers may have a small section for making ice cubes.
The most common type is “compressor refrigerator”. They are characteristic for their noise. For places that need quiet running refrigerators absorption refrigerators or thermo-electric Peltier units are more suitable. Compressor and Peltier refrigerators are powered by electricity while absorption refrigerators can use any heat source. Peltier coolers also have no refrigerant but are thermodynamically less efficient and use more electricity. Some refrigerator units use oil or gas (natural gas or propane) or can be dual powered with both gas and electricity. Solar refrigerators and thermal mass refrigerators are designed to use less electricity. The first uses Sun to reach temperatures needed for work while the other relies on the strong insulation to keep low temperatures for longer times.
Style-wise top freezer fridges are the most popular type of refrigerator and they are least expensive. They have a freezer on top and a refrigerator at the bottom. They appeared for the first time in 1940s and are popular still. At first freezer was a part of the refrigerator (and can still be found today) while a separate freezer compartment became the industry standard during the early- to mid-1960s.
Bottom freezer refrigerators are similar to top freezer models, but with they have freezer at the bottom. Freezer can have open like a door or pull out like a drawer and refrigerator part is more accessible because it does not require bending from the person using it. They appeared in mid-1950s and can still be found today.
Side-by-side refrigerator (also known as American-style fridge) was introduced by Amana in 1949 and became popular in 1960s. Its popularity is still strong. It is built so it has left side for a freezer and the right for a refrigerator.
French-door style appeared in 1990s. It has a refrigerator in the upper part with two French doors and freezer at the bottom, most commonly made as a drawer.
Four-door French-door style is a design from mid-2000s. In the upper part it has two French doors for refrigerator, while at the bottom it has a freezer like a standard French-door refrigerator. It also has an extra door above the freezer which can work as a refrigerator or freezer.
Refrigerated drawers are installed under one’s kitchen countertop, like a dishwasher. They are not too are not energy efficient because it is hard to isolate them properly.
Compact fridges are small versions of standard refrigerators. They are used at places where space is not a commodity like dorm rooms or home offices.
Door and drawer freezers has drawers (like its name says), and the entire contents of the freezer can be pulled out on gliders when the doors are opened.
Four door style have a French door refrigerator section in the upper half and a lower section has a freezer on the left and an area that can be converted between fridge and freezer space on the right.