What is the difference between "quiet" and "taciturn?" Thanks?

Not sure if they differ at all, technically, but the connotation of taciturn is less complimentary - almost meaning "sullen".

Quite - Not talking much or not talking loudly; reserved.

Not showy; undemonstrative.

https://en.wiktionary.org/wiki/quiet

Someone who is taciturn is reserved, not loud and talkative. The word itself refers to the trait of reticence, of seeming aloof and uncommunicative. A taciturn person might be snobby, naturally quiet, or just shy.
Having its origin in the Latin tacitus, "silent," taciturn came to be used in mid-18th-century English in the sense "habitually silent." Taciturnity is often considered a negative trait, as it suggests someone uncommunicative and too quiet. Jane Austen wrote, "We are each of an unsocial, taciturn disposition, unwilling to speak, unless we expect to say something that will amaze the whole room, and be handed down to posterity with all the éclat of a proverb."

https://en.wiktionary.org/wiki/taciturn

If you are quiet, you are calm - not saying anything.

If you refer, for example, to someone's quiet confidence or quiet despair, you mean that they do not say much about the way they are feeling.

You describe someone's activities as quiet when they happen in secret or in such a way that people do not notice them.

A quiet person behaves in a calm way and is not easily made angry or upset.

https://www.collinsdictionary.com/dictionary/english/quiet

A taciturn person does not say very much and can seem unfriendly.

Synonyms: uncommunicative, reserved, reticent, unforthcoming

https://www.collinsdictionary.com/dictionary/english/taciturn

quiet
(of a person) tranquil and reserved by nature; not brash or forceful.

https://en.oxforddictionaries.com/definition/us/quiet

taciturn
(of a person) reserved or uncommunicative in speech; saying little.

https://en.oxforddictionaries.com/definition/us/taciturn

Quiet usually refers to one who says little or nothing whereas taciturn refers to one who is not communicative.

quiet: making little or no SOUND - a quiet car engine/ a quiet person
taciturn : SAYING little

They both refer to a human characteristic. "Quiet" means: not saying much; not inclined to talk a lot, but "taciturn" means: saying even less; even less-inclined to talk; using as few words as possible.