Yeah that's ridiculous. Both cases are a teacher taking advantage of a student. Both should be charged equally.
The fact that one victim is a boy and the other is a girl is irrelevant because they are both minors and the adult knows better.
I think the idea that we should treat men and women the same is noble in some ways but most people disagree with it in reality.
Most men have had their bums pinched by women or experienced some other kinds of unwanted sexual touching, especially in nightclubs or similar venues. In the vast majority of cases it doesn't bother men anywhere near as much as it bothers women.
So, what should we do? Should there be mass campaigns to criminalise millions of women, lock them in jail, put them on the sex offenders register and ban them for certain jobs (teaching, for example)? Or, should we expect women to shrug it off when men do it to them tell them to get on with it?
I'm not saying that adult women having sex with underage boys is not a problem. It clearly is and should be a criminal offence but I don't think it's the same when it's a female victim. For one thing, many teenage boys are stronger than grown women so they can stop the situation much more easily than a girl can with a grown man.