An essay by Greg Costikyan about the difference between a review and a critique and why the game industry needs more critics and fewer reviewers.
A review is a buyer’s guide. It exists to tell you about some new product that you can buy, and whether you should or should not buy it. A good review goes beyond that, and suggests who should buy it, since not everyone enjoys everything. (E.g., A romance novel may be very fine of its kind, but is quite unlikely to appeal to me, since it is not a genre I enjoy.)
Thus, Ebert is, ultimately, a reviewer; the net result of his discussion of a work is a thumbs-up or thumbs-down. Mind you, he is also an informed and intelligent watcher of film, and his discussion of a movie frequently veers in the direction of criticism; but he is not being paid to write critical works. Pauline Kael was.
Criticism is an informed discussion, by an intelligent and knowledgeable observer of a medium, of the merits and importance (or lack thereof) of a particular work. Criticism isn’t intended to help the reader decide whether or not to plunk down money on something; some readers’ purchase decisions may be influenced, but guiding their decisions is not the purpose of the critical work. Criticism is, in a sense merely “writing about” — about art, about dance, about theater, about writing, about a game–about any particular work of art. How a critical piece addresses a work, and what approach it takes, may vary widely from critic to critic, and from work to work.