All liquids are fluids but not all fluids are liquids. The scientist (or engineer) will make that distinction but the non-scientist frequently doesn't. Fluids flow. They include liquids and gases. Liquids are a type of fluid that flows and takes the shape of its container but does not expand to fill its container. (Gases do that.) Liquid is the second state of matter, between solid and gas. A crop is usually of one thing, such as a crop of wheat, a crop of bananas, or even a crop of students. A harvest can consist of one or more crops, so the harvest can consist of a crop of corn, beets, potatoes and anything else that grows on a farm or in a region or country. (Plus, we can't harvest students; it sounds like genocide.) Also, a harvest has already been brought in from the field or orchard, whereas we call something a crop as soon as it's planted. ("We lost the whole bean crop due to the flood.") This is paradoxical, because the verb "crop" means to cut.

A fluid is any substance in which the molecules are free to flow. This includes both gases and liquids. A life if is any substance in which molecules are free to flow and volume is fixed. Liquids are a subset of fluids.