Transgender / Trans*:
term for someone who does not exclusively identify as the sex assigned to them at birth. The term transgender is not indicative of gender expression, sexual orientation, hormonal makeup, physical anatomy, or how one is perceived in daily life
Sex:
refers to the phisical, biological sex a person is assigned (usually at birth) based on their physical anatomy and hormonal makeup. Despite widespread belief sex is a spectrum and not everybody falls into the male or female category. These people are called intersex or inter*.
Gender:
refers to the personal, mental "sex" identity a person has. It can be any degree of male, female, a combination of both or neither. A persons gender does not always match their sex.