This refers to the internal sense of being male, female, both, or neither.
This refers to a person whose internal gender identity does not match the sex they were assigned at birth.
This refers to someone who expresses gender identity in a wider and more flexible manner, sometimes changing from day to day. Someone who identifies as gender fluid may at times feel male and at other times feel female, or may not feel either.
*Adopted from us.reachout.com