What is the difference between natural flavour and artificial flavour?

From a chemical standpoint, natural flavours and artificial flavours contain roughly the same molecules. The difference is in the method of preparation and the source of ingredients used to prepare the flavouring.

For example, natural strawberry flavouring is a strawberry extract, whereas artificial strawberry flavouring is chemically synthesized based on molecules found in the natural flavour. Artificial flavouring is an imitation of the natural flavour.