The elements of drama are characters, setting, descriptions, dialogue, stage direction, and theme. These are the elements, without which one cannot have drama.
Performance aesthetics refers to a system of artistic standards which inform the practice of an artist, by which he/she attempts to convey his/her vision to an audience. The elements mentioned above are a list of essential aspects of a piece of work that must be present for it to qualify as "drama," in the same way that a list of ingredients in a recipe for a cake must all be put into it if the end product is to qualify as a cake.
Performance aesthetics refers to a set of standards for beauty that determines the way in which an artist chooses to express her/himself in performance, as well as the way performance work is judged by its observers. Performance aesthetics are not set in stone, as are the elements required for drama. They vary from performer to performer, from culture to culture, and from time period to time period. The elements do not vary.
Yes, there is a major difference. Bernard Beckerman says it best in Dynamics of Drama, described below.
Theatre occurs when one or more persons presents himself in actions before others. Drama occurs when one or more persons presents himself before others in imagined acts. A good example is tight-rope walking (performance theatre) vs. Marcel Marceau miming a tightrope walk (drama). Performance is now considered a sociological subject, and such acts as doctoring, teaching, presenting a law case, even butchering a steak, etc. are all examined as "performances" -- we, in these professional capacities, act "like" the profession, or like the spectator/audience "expects these professionals to act." Add to this the century-old dictate of Josh Logan, "No conflict, no drama," and the difference is clear: drama is a kind of performance, but not all performances are "dramatic" (imagined acts).