Below is a chord of passages on social versus interhuman interactions, which I believe illuminate a key difference between introverts and extraverts.

Extraverts seem to prefer social interactions, where each person plays a role as a participant in some cultural order. Introverts seem to prefer interpersonal dialogue exposing the unique particularity of the individual (which in some ways undermines cultural roles).

This preference becomes conspicuous at lunchtime. Introverts will seek a situation where intimate conversation is possible, so they’ll sneak off with two or three introvert co-conspirators, carefully avoiding extraverts, who are likely to unthinkingly change the situation to suit their own tastes, by grabbing as many people as possible on the way out of the building, and creating a situation where people will perform for one another around the table. For an extravert that is what good times are, but for an introvert it ruins the possibility of anything truly fascinating happening.

• Buber: The Social and the Interhuman — It is usual to ascribe what takes place between men to the social realm, thereby blurring a basically important line of division between two essentially different areas of human life. … we have to do here with a separate category of our existence, even a separate dimension, to use a mathematical term, and one with which we are so familiar that its peculiarity has hitherto almost escaped us. Yet insight into its peculiarity is extremely important not only for our thinking, but also for our living. … We may speak of social phenomena wherever the life of a number of men, lived with one another, bound up together, brings in its train shared experiences and reactions. But to be thus bound up together means only that each individual existence is enclosed and contained in a group existence. It does not mean that between one member and another of the group there exists any kind of personal relation. … it must be said that the leading elements in groups, especially in the later course of human history, have rather been inclined to suppress the personal relation in favour of the purely collective element. Where this latter element reigns alone or is predominant, men feel themselves to be carried by the collectivity, which lifts them out of loneliness and fear of the world and lostness. When this happens — and for modern man it is an essential happening — the life between person and person seems to retreat more and more before the advance of the collective. The collective aims at holding in check the inclination to personal life. It is as though those who are bound together in groups should in the main be concerned only with the work of the group and should turn to the personal partners, who are tolerated by the group, only in secondary meetings.
• Nietzsche: Dialogue. — In a dialogue, there is only one single refraction of thought: this is produced by the partner in conversation, the mirror in which we want to see our thoughts reflected as beautifully as possible. But how is it with two, or three, or more partners? There the conversation necessarily loses something of its individualizing refinement; the various considerations clash, cancel each other out; the phrase that pleases the one, does not accord with the character of the other. Therefore, a man interacting with several people is forced to fall back upon himself, to present the facts as they are, but rob the subject matter of that scintillating air of humanity that makes a conversation one of the most agreeable things in the world. Just listen to the tone in which men interacting with whole groups of men tend to speak; it is as if the ground bass of all speech were: “That is who I am; that is what I say; now you think what you will about it!”
• Nietzsche: The first distinction to draw regarding artworks. — Everything that is thought, written, painted, composed, even built and sculpted, belongs either to monologue art or to art before witnesses. The second category must also include the seemingly monologue art involving faith in God, the entire lyricism of prayer; for solitude does not yet exist to the pious — this invention was first made by us, the godless. I know no deeper distinction in an artist’s entire optics than this: whether he views his budding artwork (‘himself’) from the eye of the witness, or whether he ‘has forgotten the world’, which is the essential feature of all monologue art — it is based on forgetting; it is the music of forgetting.
• Nietzsche: The cynic speaks. — At the theatre, one is honest only as a mass; as an individual one lies, lies to oneself. One leaves oneself at home when one goes to the theatre; one relinquishes the right to one’s own tongue and choice, to one’s taste, even to one’s courage as one has it and exercises it within one’s own four walls against god and man. No one brings the finest senses of his art to the theatre; nor does the artist who works for the theatre: there, one is people, public, herd, woman, pharisee, voting cattle, democrat, neighbour, fellow man; there, even the most personal conscience is vanquished by the levelling magic of the “greatest number”; there, stupidity breeds lasciviousness and is contagious; there, the “neighbour” reigns; there, one becomes a neighbour’.