First we must take into account that the "Hemp" and the "Marijuana"they belong to the same botanical family as the Cannabaceae
and they are technically the same plant. The distinction between hemp and marijuana is therefore only lexical and is due to the common use of the terms. It would be more correct to always talk about hemp, both when we mean the textile variant and when we mean the psychoactive one. But let's see what the substantial differences are.
The Hemp it is considered a very useful plant, and is widely used in the textile, food and energy industries. This variety of Cannabis is practically free of cannabinoids (THC, CBD, CBG, CBN) therefore it has no psychotropic effects.

Hemp can reach very high heights (2-5 meters) and has internodes that are distant from each other.

Hemp crops present themselves as valid alternatives to cotton crops, which are often criticized for their environmental impact, both for the use of pesticides and for the use of huge water resources. The Hemp plant is more sustainable: requires significantly less use of pesticides and fertilizers, furthermore the roots of the cannabis plant absorb polluting metals and transform them into harmless substances, without compromising their growth. Recently, Italian farmers in the Taranto area, in the south of the country, have used industrial hemp to restore life to lands poisoned by one of the largest steel mills in Europe.


The term Marijuana means the cannabis plant with a high number of cannabinoids, such as the famous THC (tetrahydrocannabinol) or CBD (cannabidiol) and has psychotropic and medicinal effects, widely used to fight or counteract the onset of many diseases.
But where does this term come from? The etymology of the term marijuana is unknown. Originally this was the name commonly used in Mexico (marihuana) to indicate the variety of hemp called Indian, where intended for consumption as a narcotic substance. The international spread of the term marijuana to more generically designate the hemp plant, regardless of use, is due to a vigorous media campaign promoted in the USA during the 1930s by the newspaper magnate William Randolph Hearst, who adopted a Mexican word since Mexico was then considered a hostile nation in the USA. The scandalous tones of his newspapers created a climate of aversion in public opinion for the hemp plant which would lead to its prohibition by the president of the United States Franklin Delano Roosevelt, who on 14 June 1937 signed the Marihuana Tax Act, a bill which, in effect, outlawed any use of hemp by imposing an unworkable tax on any use of the plant.

At the end of the congressional consultations of 1937, the American Medical Association (American Medical Association) fought hard against prohibition also linked to the medical use of marijuana. The testimony of Dr. Williams C. Woodward highlights harsh criticism of the process and its intent, through his response to lawmakers:
"In all that we have heard thus far, no mention has been made of abuse by any physician, or overdispensing by any pharmacist. Yet the burden of this bill falls heavily upon the very physicians and pharmacists, and, I express my opinion, even more heavily, if possible, upon all the farmers of our Nation.
We still cannot understand, Mr Chairman, why the bill was organized in secret, during the last two years, without any initiative, not even relating to the profession in question. No medical person could identify with this bill, even without reading it all the way through, simply because marijuana is not a drug but merely a name attached to Cannabis."
In summary, we can say that the Hemp it is mostly an exceptional and versatile fiber plant, suitable for a thousand and more occasions, which could be much more useful than it is today, due to its still limited use as a substitute for plastic.
The Marijuana, also known as Cannabis Sativa or Indica, is a noble, medicinal and therapeutic plant, used in medicine for multiple purposes and uses. Over the years the genetics of this plant have been refined through selected crosses to increase yields, flavors and cannabinoid levels.
Below is a table with the substantial differences between Marijuana and Hemp:

