The external manifestation of a person’s gender identity, which may or may not conform to the socially-defined behaviors and external characteristics that are commonly referred to as either masculine or feminine. These behaviors and characteristics are expressed through carriage (movement), dress, grooming, hairstyles, jewelry, mannerisms, physical characteristics, social interactions, and speech patterns (voice).
Those people whose gender expression is (1) neither masculine nor feminine or (2) different from traditional or stereotypic expectations of
how a man or woman should appear or behave are sometimes referred to as gender non-conforming.
Cross-dressers generally express the gender that matches the clothing they are wearing when they are cross-dressing. In most cases, their gender expression while cross-dressing does not match their gender identity.

SOURCE: Fenway Institute’s. Glossary of Gender and Transgender Terms. Available at www.thefenwayinstitute.org