looki it isn't because you have 2 children. If you had had your 2nd child first it sounds as if you would have had your life thrown into chaos from the start of parenthood.
Things go in phases and a placid baby/ toddler / preschooler can end up having a "difficult" phase for a few years as a child or teen, and a wild-child can morph into a "perfect" school kid.
My DC1 was very restaurant friendly (but a moderately bad sleeper til she was nearly 2, and really quite bad as a baby under 9 months), my DC2 was not capable of sitting still but a good sleeper. So we had less of the good/ difficult divide - maybe that made it easier (I was so happy DC2 slept that I gladly gave up the odd meal in a restaurant for a few years).
Also managing expectations is incredibly important - if you go into parenthood expecting to carry on as you did pre kids but with a cute, charming little cherrub in tow you are mostly headed for massive disappointment - you were lucky as can be to get away with it with DC1, but DC2 has brought you crashing back to earth by the sound of things - an only child could have done the same to you right from the start, with a different temperament.
Perhaps those of us who found 2 easy were a little bit more realistic in our expectations, so didn't feel the world ended when we couldn't go out for evening restaurant meals etc.
Actually I found going from 2-3 children hardest perhaps because my expectations were then unrealistic - everyone says 2-3 is easy as nothing really changes, but it really, really did (partly because he was such a poor sleeper, but also a more "ferrel" child than the older 2 as a toddler - he climbed vertical surfaces like a thing possessed ... I didn't need stair gates for the older 2 but I needed door frame and bookshelf gates for DC3 :o )