Cannabis is a family of plants with two primary classifications — Indica and Sativa. While marijuana can be considered a member of either the Indica or Sativa families, Hemp is a member of the Cannabis Sativa family.
Hemp vs Marijuana: Composition
Because Hemp and Marijuana both derive from the Cannabis Sativa family they share certain similarities but their biological structure is completely different. Hemp and Marijuana have a very different composition.
Cannabis contains different compounds called Cannabinoids. The most dominant are Tetrahydrocannabinol (THC) and Cannabidiol(CBD).
Both Cannabinoids have shown to provide profound benefits to the human body; however, THC induces psychoactive effects (gets the user “high”), while CBD does not contain any psychoactive properties. Hemp contains a very low concentration of THC.
Hemp and Marijuana are grown for very different purposes:

Also read What is CBD?