Let's talk about bi. Essentially it means two, and it comes up a lot in LGBTQ delineations. Ok, so... there's gender identity, that's how you feel. It is the way you are most comfortable in society. You might not be perfect at it, but it is who you identify being. In your case, you feel male, you say you are masculine, so you presumably have a "binary" gender identity of male. When someone uses the term binary, they mean male or female genders. Like coding, it's all 1's and 0's. It is possible to identify outside of the standard male/female concepts. This is where you find descriptors like trans, pan, androgyny, cis, poly, queer, etc. Bi-gender also refers to gender identity, and this means a person feels 2 genders, distinctly, either at the same time or switching between them. Sexuality is simply what you find arousing. In this, bisexual would mean you experience arousal for 2 genders, typically male and female. Terms such as bi, homo, hetero, trans, etc. fit in here. If you identify as male, and you are sexually aroused by men, you would be a homosexual male. If you are not just capable of being aroused by women, but enjoy the arousal of both men and women, you would be bisexual. The degree from which you go from homo/hetero to bisexual is up to you. Biological gender is strictly referring to chromosomal gender. Some people will include genitalia in this definition, but intersex people are born along a spectrum where this is not as clearly defined and it is especially important to allow them to develop their gender identity, rather than having it assigned at birth.