There are children playing in the snow and one of them is making a snowball.
Two brothers have a snowball fight.
Just because there are children playing in the snow doesn't mean they are two and they are brothers or having a snowball fight
Just because they are children does not mean that they are brothers and just because one is making a snowball does not mean that they are necessarily having a snowball fight.
Children could have different relationships and are not necessarily two brothers. Making a snowball does not mean it will be used in a fight.