Bisexuality describes a sexual orientation, because refer to people who are sexually attracted to both genders, for example a man who likes sexually women and men.
Transgender isn't a best describer of sexual orientation because specifically refers to people who doesn't field identify with their gender. A transgender person not necessarily is homosexual for example, there are cases where women don't feel themselves as such, but they still like men.
When relaying the details of what happened in a conflict or when trying to solve it, it is best and most helpful when people are informed of the specifics as to not miss any vital details that might impact the decision or resolution.
