FRER vs Dollar Tree New Choice

Both read 25 miu/ml, right? (Can't find what FRER reads on package right now, but I swear that's what it reads). So why can FRER read "sooner" than New Choice? I took a New Choice today even though it says wait till missed period (I'm due Sat 13th and yes I'm crazy) and of course it read negative, but if they have the same sensitivity, which I think they do, why does one say wait? I'm new to this all.