Difference in Clearblue Tests?

Stacey • One boy, one girl, Two in Heaven and another on the way. Endo Warrior, Bicornuate Uterus

Just wondering what the difference is. I bought a 2 pack of ones that say 6 days sooner, and only a verticals line appears if your pregnant. I also bought a pack that comes with a digital but that one a cross appears if your pregnant. I got a super faint line earlier on a dollar store one so I bought these. I got a super faint line on the vertical one but nothing on the cross one....what’s the deal lol.