They differ, but so do our preferences, abilities to deal with/tolerate different things, and expectations.
By expectations, I mean that to me a 90 minute stretch in a next2me crib doesn't sound that bad. It's not great, but it's kind of what babies do. Equally for feeding every 2-3 hours. Frankly, as older kids, they still 'feed' every 2-3 hours (meals and snacks etc), and you've got to put more thought into what to give them than just being milk.
But I'm suited to newborns, less so to the whirlwind that is toddler hood (fun but exhausting). Others find newborns hard.
And yes, some are easier/harder than others. My first was a lot easier than my second (woke hourly from 6-18m) and was a v colicky newborn.
Think of it like a group of people starting a new job. Gill might like working with the customers but finds the IT side hard. Tom is an IT whiz but struggles with timekeeping. Sarah finds it all fine, which is irritating, and Sally is struggling with the newness of it all, but once she gets upto speed she'll be amazing.
Having a baby is no different, except that your babies are unique and have they own challenges as well. Then throw in differing support networks, differing recoveries from birth etc, and is it any wonder your experiences vary?
Just because you find this bit hard doesn't mean you aren't, and won't be an amazing mum. That's like thinking the first 100m of a marathon will determine the outcome.