Denis Dutton in the Encyclopedia of Applied Ethics:
FORGERY and PLAGIARISM are both forms of fraud. In committing art forgery I claim my work is by another person. As a plagiarist, I claim another person’s work is my own. In forgery, someone’s name is stolen in order to add value to the wrong work; in plagiarism someone’s work is stolen in order to give credit to the wrong author.
I. THE PROBLEM OF FORGERY AND PLAGIARISM
The art world is as much infected as other areas of human enterprise by greed and ambition. Artists and art dealers seek recognition and wealth, and they often deal with art collectors more interested in the investment potential of their acquisitions than in intrinsic aesthetic merit. In this climate of values and desires, it is not surprising that poseurs and frauds will flourish. Works of sculpture and painting are material objects whose sometimes immense monetary value derives generally from two aspects: (1) the aesthetic qualities they embody, and (2) who made them and when. The reputations of artists are built on what history and taste decides is high aesthetic quality; forgery is an attempt to cash in on such established reputations.
Forgery and plagiarism are normally defined in terms of work presented to a buyer or audience with the intention to deceive. Fraudulent intention, either by the artist or by a subsequent owner, is necessary for a work to be a forgery; this distinguishes forgeries from honest copies and merely mistaken attributions. But while unintentional forgery is impossible (I cannot simply out of mistake sign a painting I have just finished with “Rembrandt”), it is possible to unintentionally plagiarize.
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