A CO2 is simply a botanical extract that uses liquid carbon dioxide as a solvent to pull out the valuable components from the plant material.  This is accomplished by putting the CO2 under high pressure to force it into a liquid state.  After the extraction is complete the system is brought back to atmospheric conditions, and the CO2 returns to its normal gaseous state.  Once this happens the gas evaporates away, leaving behind the cleanest, and highest quality extract possible.  The end product is completely free of any solvent residues.  CO2s are superior to essential oils because they contain the heavier, more therapeutically active components that are not accessible by steam distillation methods.  When this method is used and essential oils are obtained by a high temperature distillation process, the reactions of the native oil occur with water giving an altered oil.  Thus essential oils are not a true natural product but a naturally derived product.  The CO2 is a true natural product, the pure, unaltered essence of the plant.