You never fully understand “no two kids are alike” until you have more than one!
My husband and I are the parents to 2 daughters (13 & 6) that are like night and day. When my oldest was born she was the calmest baby ever. She slept through the night by the time she was 10 weeks old and has been pretty independent all her life.
My youngest daughter was a preemie, in the NICU for a week, had bleeding on her brain (possibly caused by birth trauma) and pretty much cried for the first 10 weeks.
Everyone always says to not compare your kids but sometimes it’s hard. My oldest was reading on a 3rd grade level when she was in Kindergarten and my youngest is struggling and still behind with her reading in 1st grade. The other night she started crying while we were doing homework and it literally broke my heart!