My kids are 4 years apart.
I have a boy and girl.
What I did and do... with my Eldest (the girl)... is I simply explain to her, in ways she will understand... about Baby development.
I tell her... baby cannot do what she does... not yet. Babies cry/feed/sleep/wake at night. They don't know what she knows... they are only learning and do NOT understand everything yet etc. At each age juncture... I explained to my Eldest about "why" "how come" her younger brother acts as he does. He is YOUNGER... he does not know how to do things... he is not coordinated like her, he is a baby. They are not toys... you need to be gently with them etc.
I explained it to her in a way that SHE felt "privy" to the information... that she was 'older' and 'special'... and so, she is LUCKY etc.
Her little brother is now 4 years old... and still, I explain child development to her... so she 'understands' and builds 'empathy' for her little brother and his age related stages/phases. She understands. Because we explain it to her.
I also tell her that she is not an 'example' for her little brother nor do I expect her to be, she does not have to share everything, her things are special and she can tell me, she is a child herself and just because she is the 'oldest' that does not mean I EXPECT her to be flawless. She is still just herself.
I emphasize that they have each other, we are family... that means looking out for each other... that is what a brother and sister are.... and she can 'teach' her brother things too... and show him what she knows. My daughter LOVES "teaching" her brother things. She understands if he is reflecting his age. They are 2 peas in a pod.
We don't scold or punish her any different just because she is the Eldest... that is not a 'default' reason, just being older. She didn't ask to be older. But that it takes TWO to start an irritation and two to STOP it... too. Not ONLY her all the time getting reprimanded just because she is the Eldest. Fairness.
For us, as a result... our kids get along, well. We don't compare them etc. But each one is different... so we handle each one, per their personality and what works or not, per child.
And yes, boys are VERY physical... and active. My son plays rough with our daughter. She gets bonked around a lot sometimes. So we teach him about being a "gentleman" and not hitting his sister... to 'care' about her too.... and if he mistakenly does bonk her too hard... then we speak to him and they both talk to each other and say sorry and hug etc.
If my son, mistakenly is too rough... we 'allow' him to express what was going on... and he'll often say he TRIED to be gentle and "tried his best...." and we know he was sincere. So that is good.... learning HOW to 'express' themselves... and their transgressions, too.
We encourage our kids to "try their best...." and to protect each other... to be loving. They do, understand. They will even tell each other "I love you... I"m sorry.... " even if mad.
It is about teaching the child as well, about how to navigate themselves and how to make a 'mistake' or transgression better.... cooperatively.
all the best,
Susan