To a scientist, an oil is a fat. However, it is common culinary practice to use the term 'fat' for those fats that are in a solid state while at room temperature. Those that are liquid at room temperature are called oils.
Fats from animals are solid and, generally, fats from vegetables are liquid at room temperature. The notable exceptions are vegetable oils from the coconut and palm kernel. Chemically speaking, there is less difference between animal and vegetable fats than most people would suspect. Even though their saturation and cholesterol profiles do differ, both fats are made up of a glycerol molecule linked with three fatty acids. They share the attributes of being water-insoluble and having a greasy feel.