From Gramsci's principle of coherence, one can define a position that is even more fundamentally social than that of 'socio-linguistics' – a discipline that is encapsulated by the primacy of (objective) language over its (subjective) practical and political use. Modern linguistics bases this dichotomy between language system and language use on Ferdinand de Saussure, the Swiss linguist who was the first to try and make linguistics into an independent discipline. The division Gramsci establishes between lingua and linguaggio seems to be borrowed directly or indirectly from Saussure (Hoare and Smith [p. 554:] (in PN 348n32), Mansfield (1984: 119n3); Salamini (1981: 31-32)). To the extent that Gramsci adopted this dichotomy, this may be seen as a token of his 'modernity'. However, the fact that he starts out from social differences, which have to be organized by language, makes him transcend this epistemological bias.
For Saussure (1979), the system (langue) is the socially unifying knowledge of language that people share, while its use (parole) is individual. Both are to be combined in one simple concept of language (langage). Saussure does not quite succeed in realizing this combination, except perhaps when he asserts that the establishment of the identity or non-identity of an element of language implies 'a subjective element common to all people' (Saussure, as quoted by De Mauro (1969: 154)). The subjective and the objective thus converge on their social consequences. The concept of the community as a precondition on calling anything a sign is an idea that is also developed by Gramsci. In spite of this analogy, the importance of Saussure's influence on Gramsci should not be overestimated. The subjectivist stamp that Croce put on Italian linguistics overruled Saussure's inclination to privilege the objective system over the individual 'esthetics' of parole (Leroy (1966: 134-136); De Mauro (1979: 375, 397-400)).  The individual activity of the Spirit (made up of parole, concrete words) he called linguaggio, with lingua as a collective product of this activity (cf. Leroy (1966: 136n, 129); Croce (1966)). This distinction evokes the Saussurean dichotomy, yet inverts the determinism: Whereas Saussure attempts to derive the individual (parole) from the common (langue), Bertoni derives the common (lingua) from the individual (linguaggio).
Gramsci, however, does not seem to be trapped in this determinist dilemma. His unemphatic use of the opposition between lingua and linguaggio does not justify his confinement within the limits of modern linguistics. Yet, it may be fruitful to explore his use of both concepts a little further. Linguaggio can be read as connoting 'non-organic, arbitrary language', as opposed to a more organized lingua (cf. Gramsci (1984b)). Gramsci uses linguaggio, for example, for the language of works of art, which Croce too easily identifies with lingua. Another question in this connection is whether language education (lingua) should have its only source in the living language (linguaggio). This question is answered affirmatively by the idealist philosopher of the 'pure act' (and fascist minister of education) Gentile, who does not see any need to teach a unified language. Gramsci does hold that the unified language confuses the popular language, but he keeps striving for a unity of its own for non-hegemonic groups. He considers Gentile's denial of this need "a 'liberalism' of the most bizarre and eccentric stripe". This way, "the only thing excluded is the [p. 555:] unitarily organized intervention in the process of learning the language (lingua)" (CW 186-187). This excludes the popular masses from learning the cultured language. In everyday life, the study of grammar never stops. 
In short, the living language (linguaggio) is a heterogeneous and confused, still to be organized stream of acts (but it is not 'subjective'). Lingua, on the contrary, already has some coherence (which, in its turn, is not 'objective', but historical: a stage of the political struggle). Lingua is necessary to supplement linguaggio, in order for people to avoid isolation and to organize their language (community).
Thus, Gramsci avoids Croce's subjectivism (with Bertoni and Gentile as its excesses). Not every 'creation' is correct: linguistic errors, just as political ones, do occur. "An error is an artificial, rationalistic, willed creation which does not take hold because it reveals nothing, it is peculiar to the individual outside of society" (CW 177). Therefore, Gramsci equates language (lingua) with history, and non-language with arbitrariness. This might seem in opposition to Saussure, who calls any sign within langue arbitrary, from an epistemological point of view. For Gramsci, the degree of 'necessity' of that which is uttered in practice, is historical. In this way, he also avoids the objectivism we know from the Saussurean tradition, but which had, for him, probably rather a Neogrammarian look. In fact, the Neogrammarian concept of 'sound laws' was criticized also by Saussure: we cannot establish identities of signs within langue (Saussure (1979: 150-154, 246-250)). Langue, as an epistemologically empty form or scheme of differences, is filled in (and changed) historically and socially within parole, the concrete (and unrepeatable) individual execution of language. In return, it socially governs the latter (Saussure (1979: 30); De Mauro (1979: 419-422)). This reciprocity between parole and langue suggests that Saussure is more of a 'Gramscian' than is usually recognized. 
Gramsci's distinction between more 'coherent' (or organized) and less 'coherent' languages fecundates, in a practical way, the so-called dichotomy between 'objective' langue and 'subjective' parole. In this way, Gramsci affirms that systematicity takes shape in political action, and not by eternal laws. Language is to be understood not merely as a verbal expression, to be photographed at a certain time and place of grammar, hence not as pure [p. 556:] system, but as a collection of images and ways of expression that are not implied by grammar (i.e. as living language 'use') (Rosiello (1970: 357); cf. (PN 353)). Gramsci's quest is not for a foundation of language: it is for a coherence that is not yet there, but that is needed for social unity. It is, therefore, of no avail to reduce 'language' to psychological or sociological essences. It is "a collective term which does not presuppose any single thing existing in time and space. (...) the fact of 'language' is in reality a multiplicity of facts more or less organically coherent and co-ordinated" (PN 349; Rosiello (1970: 351)).