Complex sentence: In common speech, the words "perspective" and "viewpoint" tend to be used interchangeably; however, in art, aerial perspective does not imply an aerial viewpoint, such as that exemplified by aerial photography.
Split into simpler sentences: In common speech, people tend to use the words "perspective" and "viewpoint" interchangeably. In art, however, aerial perspective does not imply an aerial viewpoint, such as in aerial photography.