These are Cannabinoids that cannot be found in nature.
There are tons of Cannnabinoids in Cannabis, and even some that can be found in other places.
But even more can be made in a lab.
These are known as "Synthetic Cannabinoids"
Most of them are known as "JWH-xxx" such as JWH-018, which was recently made illegal in the USA.
But there are also others, such as AM-2201, or CPxxxx.
These "Synthetic" Cannabinoids hit the same receptors in your brain, as when you are smoking weed.
would have similar effects, but not exactly the same, because they
would target different specific areas of the receptor with varied force.
THC might hit the CB1 receptor hard, for a short time. While maybe JWH
hits the CB2 receptor hard for a short time, but the CB1 receptor hardly
at all. Which would cause an almost 100% different feeling.