Transgender refers to individuals' whose gender identification (self identification as a man, woman, neither or both) differs from the "assigned" gender (identification by others based on physical or genetic sex.)  It does not not imply any specific form of sexual orientation as transgender people may identify as heterosexual, homosexual, bisexual, pansexual, polysexual or asexual.  Transgender includes a number of overlapping categories:  cross dressers (CD, transvestites (TV), andrognyes, drag kings or queens and transexuals.  

Transsexual people identify as, or desire to be accepted as a member of a different sex than they were assigned at birth.  Many transsexual people have a wish to alter their bodies to conform to their identity.  These physical changes are known collectively as gender reassignment therapy and can include horomore replacement therapies and sex reassignment therapy.

Current diagnosis criterion (from DSM-5) for transsexual people is called "gender identity disorder", a change from previously diagnostic language which referred to the disorder as transsexualism.  This diagnostic label is often needed to obtain sex assignment therapy with health insurance coverage, though it can also result in stigmatization.  Not everyone with gender identity disorder has a desire for sexual rassignment therapy.

Helping professionals should be aware of the differences between transsexuals and transgendered people as well as the special challenges faced by them.