Alright, as you smoke more weed you will become to understand the different strains of cannabis. There are different species, but mainly classified into C. sativa and C. indica. Sativa more of a mind high, and Indica more of a body high (or so they say).
However, on the street you will find basically two types, Swag and Chronic.
Swag
A.K.A. reg, dirt, and if its really shitty, bobby brown
Is the normal, cheap stuff you will find. Why it is cheap is determined by its THC volume found in the buds. These normally have about 5-8% THC in them. This is due to the particular strain, and growing methods the crop has undergone, if it wasn't given enough sunlight or darkness, or if cultivated to early, it wouldn't reach its potential THC level. And since its just swag, growers usually do not care if the plant has been pollinated and you will get a seeds in your stash. Its just the price you pay. You can tell by looking and smelling the buds to get an idea of what it is. The greener, the better. The more stems and seeds you find, the less your getting for your dollar.
Chronic
A.K.A Kill, hydro (or just dro), kickass shit.
Is the more THC potent strain of marijuana. This is achieved due to the particular strain and its growing methods as well. With all the different cross-breeding some chronic can reach up to 10% to unheard of 15% THC in the buds. Alot of chronic found is grown hydroponicly, which means that it is grown in water and is said to be more potent than growing outdoors. (I'm not sure about this, you have to ask people who grow to get the scoop, I just thought it was a more efficient system is all) You will not find many seeds in this batch, which is because the growers will not allow the plant to be pollinated for both potency and not wanting the strain to be released to the buyer. Generally, the chronic will have little "crystals" you can see on the buds, or different "hairs" and has a particular odor to it. (delicious)
If your gonna grow, go dro. Cause if you get busted, they don't nail you for your THC potency, just your amount.
Sorry for the rambling, I'm blown outta my mind here.