It does make a difference which term you use, especially in visitor studies
and evaluation.  Exhibit usually refers to a single element within a group of
elements that make up a coherent exhibition.  Some museums have exhibits that
stand alone and are a group of exhibits, not an exhibition.  A room with
contemporary art objects chosen with a theme in mind is probably an
exhibition.  A room with a science topic demonstrated through a variety of
elements can be an exhibition.  When evaluating visitor responses, it is
important to report whether individual elements or whole entities are being
considered.
---B. Serrell