How do natural essential oils differ from reconstituted synthetic oils?

Natural essential oils are highly volatile substances isolated from plants through physical processes such as steam distillation, enfleurage, or expression. These oils are complex mixtures containing anywhere from a few dozen to several hundred individual compounds, including trace ingredients that are often unidentified but essential for providing the oil's characteristic, natural aroma.1

In contrast, reconstituted synthetic oils are created by blending individual synthetic chemical components in an attempt to duplicate the natural product. These synthetic versions differ from natural oils in two primary ways:1

• Missing Components: Reconstituted oils typically lack the specific trace ingredients found in natural oils, which often results in the absence of certain subtle odour notes.1
• Chemical Odour: They frequently possess a more "chemical" scent, caused by trace impurities present in the synthetic chemicals that are distinct from the natural components found in plant-derived oils.1

While synthetic chemicals are useful for extending supplies or creating imitation flavourings, they generally struggle to perfectly replicate the complexity of the natural substance.12