^ Pretty much sums it up. AAS is easily made just about anywhere, unsterile conditions and poor manufacturing practices can cause an issue for the user in rare occasions however. "Human grade" generally refers to gear that is produced under GMP or "good manufacturing practices" standards. FDA approval is even better, though I personally would consider "human grade" from most countries pretty safe. Even Iran produces pharmaceutical test that is pretty well respected as true human grade.
Basically when you go with HG you're paying extra money for the insurance that the gear is dosed properly and sterile. To be 100% honest I think there are many very good UG labs, but there are also very shady ones. If one is looking to do their own HRT I think human grade is the way to go as costs will be limited, in other cases doing your homework and finding a respected UGL may be your best option.