Within the Cannabis plant, there is a classification of compounds known as cannabinoids. Among these are CBD and THC, along with over a hundred others which scientists have discovered naturally occurring within different Cannabis strains.
There are two kinds of CBD Oils: Full spectrum CBD is an extract that contains all compounds found naturally occurring in the plant, including terpenes, essential oils, and other cannabinoids. Also contains THC which is the cannabinoid responsible for creating "a high" effect.
The Broad Spectrum contains everything that Full Spectrum does but without the THC.