The 2 brothers are too similar. I can't differentiate them.

try using their hairstyle to differentiate! older bro hair is more like straight and not styled while pilwoo’s hair has that gelled slick back hair.

Really, I can tell them apart easily. Pilwoo has a more confident look to him. His eyes & hairstyle give off a more "bad boyish" look to him. The other has a more tamed "Good boy" look, & always looks like a fake innocent character, definitely not my type of character. His hair is down & looks like a prim & proper young master.