Transsexual is a term sometimes used to describe transgender people. Transsexual predates the term transgender, but has become less popular as it may imply that sex characteristics are more important than gender identity.
In some cases, transsexual is used to refer to a subset of the transgender community. This may be only those who medically transition or plan to do so, as this changes their sex characteristics. Alternately, it sometimes refers to only those transgender people within the gender binary, i.e. trans men and trans women, or only to those who experience dysphoria.
Although it is no longer widely used as an umbrella term, transsexual is sometimes used as an identity by individuals as a matter of personal preference.