It's just that Lugol's at the 5% solution is less drops taken, then the 2%. I can't say if it's better. I read that it said sometimes the more diluted it is, can help a person to absorb it better, so I think with some experimentation on your part and coming here to read a lot and read other people's experiences you'll find your way just fine. At least you have begun the journey! You could try painting one on your inner arm, and one on another place, like one of your breasts perhaps, or your upper thigh. Just to see what happens. Both the 1" round is good.