Question: what is the difference between a lipid and a fatty acid?
Answer: Lipids are a larger class of molecules while fatty acids form a small part of it. Fatty acids are long chain (usually 14–20 C-atoms in length) hydrocarbons with a carboxylic acid group at one end. They can either be saturated (no double bonds) or unsaturated (one or more double bonds along the C-chain).