While hemp and marijuana are from the same plant, people usually use there terms to talk about two different varieties of the plant. Varieties grown to make hemp rope and other products you see on the shelves (including the varieties Jefferson and others grew during the 1700s) have a whole lot less of the chemical that makes marijuana users feel high. Those varieties are sometimes called “industrial hemp.” Varieties grown for use as a drug have been specifically bred to have lots of THC, or delta-9-tetrahydrocannabinol, which is the chemical that makes users feel high.