Medical marijuana and recreational marijuana are two different types of cannabis products. Medical marijuana is used for medicinal purposes and can only be obtained by a prescription from a doctor. Recreational marijuana refers to the use of cannabis for personal enjoyment, and it can be bought in shops or grown at home without any restrictions. The main active compounds in cannabis (for both medical and recreational use) are cannabinoids such as THC and CBD.
How can cannabis be consumed?
Cannabis can be consumed through smoking, vaporizing, oral ingestion or topical applications. The feeling of being ‘High’ is caused by THC which works by binding to cannabinoid receptors in the brain and other organs throughout the body and activating them. Cannabinoid receptors are very similar to opioid receptors which influence pain perception, but instead affect mood and cognition rather than physical function. However, they also share some operational similarities with opioid receptors: after prolonged use, cannabinoid receptor sites degrade resulting in a decrease in activation strength for both types of receptor. This results in tolerance wherein more marijuana has to be consumed to achieve the same effects. If cannabinoid receptor sites are allowed to normalize, then withdrawal symptoms can occur if marijuana consumption is suddenly reduced or stopped completely. 
How can weed be used for medicinal purposes?
Marijuana is typically used for medicinal purposes because it reduces Nausea and vomiting, induces appetite in chemotherapy or AIDS patients, reduces Chronic Pain and neuropathic discomfort associated with Multiple Sclerosis, relieves spasticity in people with neurological disorders such as epilepsy or paraplegia & eases Anxiety & sleep disturbances. There is also some evidence that cannabis can be beneficial for psychiatric problems such as psychosis, Depression & Bipolar Disorder. Potentially even schizophrenic symptoms have been reported to improve after smoking marijuana. However, the link between cannabis use and psychiatric disorders has been hotly debated.
Although most research into the therapeutic effects of cannabinoids is in its infancy, many studies have yielded encouraging results that have stimulated an increased interest in cannabinoid-based medicine with a lot of resources being committed to this field.  There exists a wide range of over 150 different cannabinoids in cannabis, each having unique properties with differing medical applications. The most extensively researched compounds include THC , CBD & CBN.
In terms of recreational use, marijuana is typically used for its euphoric mood altering effects resulting from the main psychoactive ingredient: THC. In particular it increases sensory perception such as watching films or going on social outings with friends, from food & sex and also promotes