Did you know there were three different types of lavender? ...I certainly did not.  Apparently there is

Spike Lavender grows in scrub land between 0 et 600 metres of altitue. It is a large plant with several branchings, each stalk bears many, small flowers. It reproduces itself by seeding. Little used in France because its fragrance is too strong (too camphorated), it does serve in Spain and Portugal as a thinner for oil paints and on porcelain.

Hybrid Lavender grows between 0 and 800 metres altitude anywhere in the world. It is a large plant, has 2 branchings and forms a highly developed cluster in the form of a ball. It is a hybrid, which means a cross between fine lavender and spike lavender. Because it is sterile, Man propagates it with cuttings. It was brought into cultivation starting in 1950, and since it has been confused with fine lavender. That is wrong because it has a stronger fragrance, much less subtle than the fine lavender, and it can not used for its medicinal properties. Its use remains industrial, for scenting house cleaning products and detergents. The flower is used for making the little sachets of lavender.
It takes about 40 kg of flowers to obtain 1 litre of its essential oil (a much more interesting yield than from the fine lavender!).

Fine Lavender which grows on the dry Provençal mountains above 800 metres altitude. It is a small plant with only one flower on each stem. It reproduces itself by seeding. Used since the beginning of time for it medicinal properties, it was the "blue gold" of the region when it was sought after by the largest perfume makers for its very delicate fragrance, hence the name, used by producers, of "fine lavender". It takes approximately 130 kg of flowers to obtain, by distillation, 1 litre of essential oil. In a good year, one hectare of plants could produce up to 25 litres of essential oil.