Dramatic, theatrical, dramaturgic, melodramatic, histrionic are not close synonyms although all imply special reference to plays as performed by actors or to the effects which are produced by acted plays.
Dramatic basically denotes relationship to the drama as written or as produced. It may imply an effect or a combination of effects appropriate to the drama (as a stirring of the imagination and emotions by vivid and expressive action, speech, and gesture, or by the exciting complications of a plot).
Theatrical denotes relationship to the theater. It may imply effects appropriate to the theater as the place where plays are produced, and to the demands which its limitations, its convention, and, often, its need of financial success make both upon a play and its performance; the term therefore usually implies a marked degree of artificiality or conventionality, a direct and sometimes a blatant appeal to the senses and emotions, and often an overdoing or exaggeration in gesture, in speech, or in action.
Dramaturgic, which stresses the technical aspects of the drama and its presentation, may be used in place of theatrical when the more or less derogatory connotations of that word are to be avoided and the emphasis is upon those elements in a play which fit it for representation in a theater.
Melodramatic implies a manner characteristic of melodrama; it, therefore, usually connotes exaggerated emotionalism or inappropriate theatricalism.
Histrionic is more limited than theatrical for it implies reference to the tones of voice, gestures, movements, and appearance characteristic of actors, especially in times before realism was attempted in dramatic performances.