Bipolar in preteens: home and school

[Cattus]

My friend’s daughter is showing lots of signs of ADHD but having researched she wonders if the behaviour are symptoms of bipolar or both.
Teachers see no evidence of anything whatsoever at school; she appear a model pupil, but behaviour at home is very different. Can that be possible with bipolar?

As far as I understand ,behaviour would be the same at home and school. If manic, she’ll be manic at school and home, if depressed she’d be the depressed at school and home.

I work in a school & my son's dad has bipolar. I've worked with many children with ADHD and have experience of my son's dad's bipolar manic phases (which can last for months) and the depressive phase. There is no way these conditions would not overlap between home and school.