Chill out and euphoria:
the main differences between CBD and THC
Tetrahydrocannabinol (THC) is the most famous component, but cannabis sativa contains other elements including Cannabidiol (CBD). THC and CBD have the same chemical structure, but they affect the body in different ways. For instance, when CBD is used in isolation it does not create a high.
What are the effects of CBD and THC?
CBD and THC have different mental and physical effects. CBD is said to have the potential to affect mood, appetite, immune response, and sleep. Whereas, THC is said to change reaction time, appetite, memory and coordination, and mental state.
Are CBD and THC legal?
In recent times, the legal status of CBD and THC has differed. CBD products are starting to become widely available in Europe. While, with some notable exceptions such as Canada and the United States, goods containing THC remain illegal.
Do CBD and THC have medical benefits?
Both CBD and THC have been judged by some professionals to have medical applications. CBD is used to help with conditions such as seizures, inflammation, pain, psychosis or mental disorders, inflammatory bowel disease, nausea, migraines, depression, and anxiety. THC is used to assist with pain, muscle spasticity, glaucoma, insomnia, low appetite, nausea, and anxiety. 
What is the chemistry of CBD and THC?
Both CBD and THC interact with your body through the endocannabinoid system, an amazing network which has an important role in regulating physiological and cognitive processes throughout the body and appears to be designed specifically to process cannabis.
CBD and THC have the identical molecular structure: 21 carbon atoms, 30 hydrogen atoms, and two oxygen atoms, but there is a contrast in the arrangement of these atoms, and it is this difference which determines the effect of the compounds on the body. 
For recreational users, how does the experience of CBD and THC differ and what happens if the two compounds are used in combination?
THC binds with the cannabinoid 1 (CB1) receptors in the brain, but when CBD is used in isolation it links only very weakly, if at all, with these receptors. It is this difference which makes THC create the high or sense of euphoria which is absent in CBD only products. 
Consumers of THC have said that the presence of greater levels of CBD in products make for a more comfortable high. This is because when CBD and THC are paired together the behaviour of CBD changes. It starts to compete with THC on the CB1 receptors.  This situation, where CBD gains an additional attribute when used in conjunction with THC, has been described as the “entourage effect”. The entourage effect can regulate some of the undesired side effects of THC. So, it’s always a good idea to introduce CBD in your cannabis experience even if you’re a THC lover.
Is there a simple metaphor that explains the difference between CBD and THC?
If CBD and THC were guests at the same party, CBD would be playing it cool: leaning against the bar sipping its favourite drink, tapping its foot to the music. While THC would be the middle of the dance floor flailing its arms around and shouting at the DJ for more.
In short, CBD is a chilled out experience, whilst THC is euphoric. What is interesting is that when the two compounds are paired together the consumer can enjoy the best of both worlds. The calmness of CBD regulates the energy of THC.