What are Synthetic and Natural Fragrances?

Whether a material is considered Natural or Synthetic is a complicated discussion. Just look it up online to see the breadth of the conversation.
Many aspects of perfumery are defined differently from one practitioner to the next.

Natural materials

Derived from a plant or animal origin and are complex blends of molecules. These materials can consist of tens to hundreds of different individual molecules. These materials are extracted using multiple processes, namely: Expression or Cold Pressing, Hydro or Steam Distillation, Solvent Extraction, and CO2 Extraction.

Synthetics materials

Synthetics are single isolated molecules. Most synthetics are derived from a petroleum origin (petroleum is rich in the four elements, hydrogen, oxygen, nitrogen and sulfur, that compose all fragrant molecules). These materials are created in a lab through a set of chemical reactions, such as heating and enzymatic reactions. (Please note that similar molecular processes take place in the processing of natural materials).

Other materials

There is a class of synthetics called Natural Isolates or Hemi Synthetics, which are single molecules that have been extracted from raw material that is plant or animal (instead of petroleum) in origin. For example, Phenyl Ethyl Alcohol which is a molecule naturally occuring in Rose, can be isolated from Geranium Leaves or Rose Petals (a natural isolate) or the exact same molecule can be constructed from rearranging the elements derived from petroleum (a synthetic).