Do you find there are many differences in refereeing girls' games vs boys' games?
Sure, there are lots of differences. Girls' games are generally thought to be "easier" to ref, because, for one, boys are more physical and aggressive with each other, and also boys usually are more open to confrontation and willing to be demonstrative with the refs, whereas teenage girls, unsurprisingly, generally don't like to interact with adult men they don't know (the vast majority of refs are men; I'm sure the gender dynamics are different with female refs).
So boys' reactions to other players' actions and to referee decisions will often be more instinctual, thoughtless, and outwardly emotional, while girls will tend to self-filter and if they have a negative outward reaction it will usually be quieter and more passive-aggressive. There's a sort of stereotyped conventional wisdom that I've sometimes heard from other referees (not sure how true it really is) that when boys get into some little conflict the second player will immediately retaliate against the first and the ref will be able to know what's going on, step in and handle it, whereas a girl who feels like another player chipped her heel or whatever will file that away and wait for the opportune moment - 45 minutes later, the next time they play, or even years later - to get back at her. And the next ref will have no idea about this history so when something randomly blows up it's like wait what the hell just happened and where did that come from?
So yeah, basically they just have different reactions to stuff, and as a ref you have to tailor your behavior to whether you're reffing girls or boys (or adults, which are a whole other can of worms). Disclaimer: these are all very broad generalizations and definitely not universal, and there are lots of times where they don't necessarily fit.
Speaking of female players...yowza!