It has, however, a sufficiently subtle difference between the expressions clusters and industrial districts, for which proper SCHMITZ (1997: 173) call attention: In what it is followed, the terms ' ' district industrial' ' ' ' cluster' ' they are, some intersubstituveis times, but valley the penalty to remember that, even so an industrial district is always to cluster, the inverse one nor always is verdadeiro' '. What SCHMITZ (1997) it wants to say, with this, is that since Marshall (1982) the analysts costumavam to use the expression industrial district to mention itself to a deep division of the work (specialization) occured between the companies. However, in the analysis contemporary, the term industrial district, beyond the division of the work (specialization), it also implies in cooperation. Already the term to cluster is mentioned only to a sectorial concentration and geographic of firms, that is, in cluster the division of the work exists (specialization), being able to have or not it factor cooperation, but not obligatorily. Here it is, therefore, the first idea on cluster (or accumulations), expression this used at the beginning of the decade of 1970, to not only characterize the Italian industrial districts, but all those existing ones in the Europe and other continents, as for example: Valley of Silicon, in California; Vilarejos of the Cholet, Valley of the River Arve, Oyonnax and Thiersna, in France; Baden-Wrttemberg, in Germany, Valley of the Bells, in Brazil (RS), etc. Done these first comments, is inferred that ' ' cluster it is an agglomeration of considerable size of firms in an area especially delimited with clearly specialization profile and in which the commerce and the specialization interfirmas is substancial.' ' (Altenburg and Meyer-Satamer apud SUZIGAN, 1999:04). As it was said before, beyond this specialization &#039 can also have the factor; ' cooperao' ' in cluster, in case that where the enterprise relations happen of interarticulada form, by means of ' ' action conjunta' ' of the economic and social agents, existing intense competition between the local companies at the same time where the firms collaborate ones with the others, forming an innovative environment where if they develop positive synergies through the reciprocal confidence, mutual learning and collective innovation. .