Something which represents the whole meaning or part of the main subject. It is directly connected with the subject.
EXAMPLE; the London Eye
This transfers the meaning from one to another and it should leave little doubt as to the intended meaning of the visual metaphor as it should draw a comparison between the similarities.
EXAMPLE; the Big Smoke - in reference to London
A symbolic image which is use to make a reference of something which has a close relationship to the subject. The image does not have to be directly linked but upon looking at the image it should be clear where it associates to
EXAMPLE; red bus, red post box - ENGLAND/LONDON