Informal vs. Unofficial — What's the Difference?

Not formal or ceremonious; casual

Not official

Not being in accord with prescribed regulations or forms; unofficial

Not acting officially

Suited for everyday wear or use

Not officially established.

Characterized by nontechnical vocabulary, simple sentence structure, and relatively few explicit transitions, as typified by spoken language

Implicitly true but withheld and/or contradicted by authority.

Not formal or ceremonious.

Not acting with official authority.

Not in accord with the usual regulations.

(pharmacology) Not listed in a national pharmacopeia etc.

Suited for everyday use.

Not having official authority or sanction;

(of language) Reflecting everyday, non-ceremonious usage.

Not officially established;

(gardening) Not organized; not structured or planned.

Not in the regular, usual, or established form; not according to official, conventional, prescribed, or customary forms or rules; irregular; hence, without ceremony; as, an informal writing, proceeding, or visit.

Deranged in mind; out of one's senses.

Not formal;

Not officially recognized or controlled;

Used of spoken and written language

Having or fostering a warm or friendly atmosphere; especially through smallness and informality;