How do carbohydrates differ from fats?

The distinctions between fats and carbohydrates:

Chemical composition and structure: Fats are esters of fatty acids and glycerol, and carbohydrates are polymers of monosaccharides, which are polyols (many OH groups) with an aldehyde or ketone functional group.

Fats are hydrophobic, while most carbohydrates are hydrophilic and smaller ones are soluble in water.

Because they can be converted to glucose, which is used to generate ATP through Glycolysis, Kreb's cycle, and the electron transport chain, carbohydrates are the preferred energy source in biological systems. Fats are less desirable because they yield less ATP and are metabolized by beta oxidation. However, the body can also convert fats to glucose (gluconeogenesis) and vice versa (formation of triglycerides from AcetylCoA).

Cell walls of plants and bacteria are composed of complex carbohydrates such as cellulose, while fats play a crucial role in the cell membrane.

Both fats and carbohydrates undergo extensive modification, and occasionally they combine to carry out specific biological functions. For example, lipid rafts—areas of the cell membrane that have different properties—are given different names by phospholipids, glycolipids, glycerophospholipids, sphingolipids, and other compounds.

Protein folding and cell-cell adhesion are aided by modifications to many proteins, such as glycosylation (combination with carbohydrates). Similarly, proteins can combine with fats to form lipoproteins, which are critical for the transport of hydrophobic fats through a cell that is mostly aqueous.

I may be overlooking a lot of important details. Please read the following sources again:

Biochemistry by Stryer is intermediate; Biochemistry by Lehninger is more advanced and has a ton of thought-provoking end-of-chapter questions.

In general, carbohydrates are more easily and quickly metabolized than fats. Carbohydrates are used as a quick source of energy, whereas fats are used as a long-term energy storage molecule. Carbohydrates and fats are composed of carbon, hydrogen, and oxygen, but in different ratios.