The division between fine arts and illustrations is that fine arts permit the viewer to contribute his own interpretations or originations to the scene whereas illustrations are “too literal” and give him the whole works.
To evoke an emotion in fine arts, the spectator must be invited to contribute part of the meaning.
In a poster, the viewer is most often intended to be clobbered.
In illustration, the viewer is intended to be informed.
A work of fine art can elicit quite different emotional contributions from one member of an audience to the next as he is left free to some degree to contribute meaning and emotion at his choice.
In fine arts, the viewer must supply something to make it complete.
Fine arts evoke some chord in the viewer’s nature or past.