appropriation, plagerism, - fancy names for copying?

Appropriation in art is the use of pre-existing objects or images with little or no transformation applied to them. The use of appropriation has played a significant role in the history of the arts (literary, visual, musical and performing arts). In the visual arts, to appropriate means to properly adopt, borrow, recycle or sample aspects (or the entire form) of human-made visual culture. Notable in this respect are the Readymades of Marcel Duchamp. Inherent in our understanding of appropriation is the concept that the new work recontextualizes whatever it borrows to create the new work. In most cases the original 'thing' remains accessible as the original, without change.
(wikipedia)

example of appropriation in photography

Marcel Duchamp

Leonardo da vinci

Plagiarism is the "wrongful appropriation" and "stealing and publication" of another author's "language, thoughts, ideas, or expressions" and the representation of them as one's own original work. The idea remains problematic with unclear definitions and unclear rules. The modern concept of plagiarism as immoral and originality as an idealemerged in Europe only in the 18th century, particularly with the Romantic movement.

Plagiarism is considered academic dishonesty and a breach of journalistic ethics. It is subject to sanctions like penalties, suspension, and even expulsion. Recently, cases of 'extreme plagiarism' have been identified in academia.

Plagiarism is not a crime per se but in academia and industry, it is a serious ethical offense, and cases of plagiarism can constitute copyright infringement.

(wikipedia)

example of plagerism in photography

(http://justcreative.com/2008/02/20/graphic-design-plagiarism-rip-offs)

A pastiche is a work of visual art, literature, theatre, or music that imitates the style or character of the work of one or more other artists. Unlike parody, pastiche celebrates, rather than mocks, the work it imitates.

The word pastiche is a French cognate of the Italian noun pasticcio, which is a pâté or pie-filling mixed from diverse ingredients.Metaphorically, pastiche and pasticcio describe works that are either composed by several authors, or that incorporate stylistic elements of other artists' work. Pastiche is an example of eclecticism in art.

example of pastiche in photography

 Milton Green’s classic shot features the American actress and Post Cereal heiress Dina Merrill regally attired in Cuban-born, American fashion designer Luis Estevez’ low-cut black crepe tribute to the famous Sargent painting. Originally published in LIFE in 1960.

(http://www.newyorksocialdiary.com/social-diary/2007/fashion-overload)

A parody (/ˈpærədi/; also called spoof, send-up or lampoon), in use, is an imitative work created to imitate, or comment on an original work, its subject, author, style, or some other target, by means of satiric or ironic imitation. As the literary theorist Linda Hutcheon puts it, "parody … is imitation, not always at the expense of the parodied text." Another critic, Simon Dentith, defines parody as "any cultural practice which provides a relatively polemical allusive imitation of another cultural production or practice." Parody may be found in art or culture, including literature, music (although "parody" in music has an earlier, somewhat different meaning than for other art forms), animation, gaming and film

examples of parody in photography

(http://www.boredpanda.com/famous-painting-remakes/)

There is a fine line between each of the above