Roland Barthes' semiotic theory includes hermeneutic codes, pro erotic codes, symbolic codes, semantic codes, and cultural codes, also known as referential codes.
Symbolic codes are images which have come to represent something else, such as a cross on a building representing Christianity or a heart symbolizing love.
Semantic codes are parts of a media product that we understand have a hidden meaning, such as the use of red and black in a horror movie signifying danger, death, and blood.