Should I choose UCs or CSUs?

Not sure if I should post here.

If my daughter holds US passport but currently studying overseas, she will be consider OOS student rather than international students, right?

But what is the difference between OOS & international students for studying at CSUs? I saw that international students need to pay a per unit fee of ~$350 to ~$400 at CSUs, so OOS students just need to pay OOS tuition and can take up to certain amount of units?

On the other hands, does UC system having the similar way of charges on tuition?