There isn't that much difference. We all know marijuana (also called as cannabis, weed, pot, dope, grass, ganja, etc.), so the only thing left to describe is hash. Hash is basically from the same plant, but it is concentrated, purified, and compressed. If marijuana is usually green and fluffy, a hash is brown and in blocks. There's not much difference in the 'high' that it gives, but some say that hash is stronger because it has more THC (the main ingredient in cannabis that's also used as an ingredient in medicines).