hydro is weed grown hydroponically. Pretty much just a generic strain but has a good potency due to the way hydroponics work.
schwag is generally generic outdoor raised, poorly dried weed. Most of the time the buds are broken up and has lots of seeds and big stems. Pretty comming in Houston which i think is due to closeness to mexico and a major port. Sometimes even has leaves broken into it. No one would every pay more than 5$ for 1.75g.
Dro is the same as hydro.
Cant help you with the lows mids highs because we dont use those terms where i live.