Simile is a trope which draws an imaginative comparison between the explicit tenor (T) and vehicle (V) foregrounding one or more points of resemblance, i. e. tertiumcomparationis (TC), the comparison being expressed by a special connective (C).
Metaphor is an imaginative identification of one concept (the tenor) with another (the vehicle) and the resultant breach of normal correspondence between concepts and words.
Like all the tropes simile may be simple or sustained (developed, extended or Homeric). In a simple simile the vehicle is expressed briefly and directly without enlargement; in a sustained simile the likeness is expressed and afterwards developed into a vivid "micro-picture".
Metaphors, like similes, may be simple or sustained. In a simple metaphor there is only one vehicle, while in a sustained metaphor there is a central vehicle supported by one or more contributary vehicles which bear reference to the central one. Coordinate metaphors. Sometimes there are a number of vehicles that are not subordinated to any central image but are separately coordinated with the tenor. In this case we speak of coordinate metaphors. Mixed metaphors. Mixed metaphor is the use of two or more vehicles which are incongruous or illogical when combined.