These terms are frequently used interchangeably, but they have distinct meanings. Edition, from a Latin word meaning "to give out," refers to (1) the format (size and shape) in which a work is published; (2) the entire number of copies (impressions) of a published work (book, magazine, newspaper) printed from a set of type in one continuous run; (3) a version of any work, printed or not, that is publicly presented, as, for instance, the latest edition of a play or opera. If a new printing involves no changes in the text or illustrations of a work, or only minor corrections, the result is not a new edition but a new impression. A thorough revision resulting in a noticeably different version is a new edition. A first edition is a work as it is or was originally published. An impression is one of a number of printings of the same edition made at different times from the same set of type.
Dictionary of problem words and expressions. Harry Shaw. 1975.