Well, these two excellent plays certainly have lots of differences that you can identify. You might like to begin by considering the classifications that have been used to describe them. Othello is considered a tragedy, because of the way in which it charts the downfall of a noble character, Othello, and results in the death of many of the principal characters. The Tempest, on the other hand, is described as a Romance by most editors, although it was originally denominated a comedy.
However, going beyond the labels that are applied to these two great plays, Othello deals with the problems of jealousy and what potentially tragic events can occur if this jealousy is given free reign. Othello's slaughtering of his wife, whom he loves, marks his final downfall and stands as a warning to all those who are susceptible to jealousy. The Tempest, on the other hand, is seen more as an allegory about Shakespeare's art as a "magician" in the theatre, and the absolute power that a playwright has. It does not end with any corpses, but it does end with the renunciation of Prospero's magic that has come so much to define him.