i live in the uk so i dunno if im right about ur slang i'm guessing shwag is shit weed pressed flat in blocks with seeds(we call it thai). correct me if me im wrong anyway the difference is it that indica is more of a full body tiresome i need to sit down and do nothing high, sativa is more of a thoughts racing heart racing kinda high.

whether its indica or sativa that doesnt determine the quality of the weed its a few factors if its grown well, dried well and the parent plants i prefer sativa but its harder to grow in doors thats why i go for an indica sativa high-bred.

hope that helped