There are many different strains of Marijuana. They are all different in potency and how it affects the body. Some have THC, which is a psychoactive ingredient that makes the users feel "high" and some do not have that same chemical.
Italian scientist have newly discovered a compound which they are calling tetrahydrocannabiphorol (THCP). They are unsure on if it could deliver a "high" 30 times more than other strands or if it won't even give the user any feeling at all. Italian scientists have also discovered CDBP which appears to be similar to CBD in that it can also help with anti-inflammatory, antioxidant and be an anti-convulsant.
You can read the full article for yourself over at CNN.com