What is the sign? What is the symbol? ¿ What is the frontier that separe the sign from the symbol? Let´s analize the etimology of each one of these concepts.
Sign: Belongs to latin "signum", and it at the same time belongs to the greek σημειόν. The sign is the smallest particle in the expresion field. In its structure two parts can be recognized: significance (conceptual image) and significant (sensorial image). Denominate sign, no only the human artificies, besides that, by example, the animal´s gestures, colors, shapes of the mineral and vegetal realm,etc. The sign can have natural significance as much as conventional. From dark origen, orphic and perhaps Pitagoric, be worthy of the singular comparation between sema (sign) and soma (structure), manifesting that way that as the same way the body is hide in the soul, in the sign is hidden the meaning. Now consider, been the carrier of the meaning isn´t the same that be the carrier of the truth, a sign is neither truth nor false.
Symbol: Belongs to latin "symbolum"and these from the greek
σύμβoλoν. The symbol is a human invention, it´s composed for more than one sign, and its meaning is just conventional. We call symbol to any signs synthesis that, ordered in a particular way, express a meaning convencionaly accepted . In the last instance, the symbol is known trough signs which shape it. For someone, as the Geertz´case, every sign that is susceptible of interpretation is a symbol. The symbol is susceptible of a truth judgement.
The diference between sign and symbol is definied by the following characteristic, as the sign can be a simple trace understood not only by the human intelligence, but also by the animals, the same thing doesn´t happen with the symbol, which, to difference of the sign, can only be understood by the man. The difference in both is of technic character, the symbol is a synthesis itself, a symbol can have many signs in its structure. We could say that the sign is the smallest part of the symbol, as the letters are the smallest part of signification in a name.
Extending the difference between sign and symbol, we can say that, the first belong to the cosmic nature field, and as a consequence, to the man; as the second belongs only to the nature human field, it´s artifice, art, invention. insomuch as the knowledge sphere, we can say that, as the sign can be recognized immediately by the sensorial image, the symbol, on the other hand, need of the association of ideas in order to be recognize it. There isn´t a symbol without a sign. By example, a cross, is a compound symbol by at least two signs, in order to get know, a horizontal straight line and other vertical straight line. Now, depending of the way in which will be disposed this straight lines (signs), we will obtain different kinds of crosses (symbols).Epysteticaly a sign lack of a true value, it means, it doesn´t have epistemic use, on the other hand, the symbol is an valid instrument for the epistemic analysis, it means, a symbol, besides of have meaning it also have a true value.
So we can say, that the frontier that separate the sign from the symbol is not other than the men.