1.) Familiarly, an exemplar is something we look to imitate or mimic: the life of a saint, the work ethic of a personal hero, the coolness of some artist, etc.
2.) This makes the exemplar (A) the imitable and (b) what spurs or brings about its likeness. Both are like form so far as form is communicable to many but not so far as form is an immanent cause, and like final causality as the source of a tendency to form but not the term of generation. If you take St. Francis as a model it isn’t he who becomes the saint.
3.) Exemplar causality is clearly present when we explain the actions of beings with cognition, but it seems true of causal relations more generally so far causes and effects share a likeness. Form, for example, is not a principle of likeness as communicated to matter but as communicated ad extra; and a final cause identifies the thing desired with the term of action so does not allow for a likeness between the two.
4.) It makes no difference here whether exemplar causality differs from formal and final causality in reality or only in account. Whether the stairs that go up and those that go down are in different locations or are the same structure used both ways makes no difference to the reality of both. If forms and final causes are real, exemplar causes are too.