What is the difference between Weed, Charas and Hash?

Weed: dried flowers of the cannabis/marijuana plant with endogenous psychoactive compounds called cannabinoids that form on the surface of the flowers and some leaves in the form of small, sticky crystal-like growth called trichomes.

Hash: any extract from the cannabis plant that concentrates the trichomes and results in an end product in a solid state. By either chemical or mechanical means, the trichomes ( normally attached to the plant) are removed and collected together and pressed to form a concentrate of cannabinoids.

Charas: a specific type of hash, the only one which is made from a live plant. Exclusive to the Indian subcontinent, in this process, the laborer rubs the flowers of the cannabis plant in his palms. The agitation dislodged the trichomes which get stuck to his palm. As this process is repeated for multiple plants, a thick layer of sticky trichomes and minimal plant matter begins to collect on the palms and aggregate. After sometime, this aggregate is removed from the palms and the process is repeated. This aggregate is charas.