Basically the same here. Oldest was reading proficiently way before preschool, my youngest is 7 and still struggling to pick out up. He's really smart, and we read to him and with him plenty, but it just doesn't click for him like my oldest. He can do math no problem and he loves science and learning in general, but reading and writing are just specifically hard.

It's weird how different things can be for kids even in the same family and environment.