The difference between Brief and Transient

When used as nouns, brief means a writ summoning one to answer to any action, whereas transient means something which is transient.

When used as adjectives, brief means of short duration, whereas transient means passing or disappearing with time.

Brief is also adverb with the meaning: briefly.

Brief is also verb with the meaning: to summarize a recent development to some person with decision-making power.

check bellow for the other definitions of Brief and Transient

Brief as an adjective:

Of short duration; happening quickly.

Examples:

"Her reign was brief but spectacular."
Brief as an adjective:

Concise; taking few words.

Examples:

"His speech of acceptance was brief but moving."
Brief as an adjective:

Occupying a small distance, area or spatial extent; short.

Examples:

"Her skirt was extremely brief but doubtless cool."
Brief as an adjective (obsolete):

Rife; common; prevalent.

Brief as a noun (legal):

A writ summoning one to answer to any action.
Brief as a noun (legal):

An answer to any action.
Brief as a noun (legal):

A memorandum of points of fact or of law for use in conducting a case.
Brief as a noun (by extension, figurative):

A position of interest or advocacy.
Brief as a noun (legal):

An attorney's legal argument in written form for submission to a court.
Brief as a noun (English law):

The material relevant to a case, delivered by a solicitor to the barrister who tries the case.
Brief as a noun:

A short news story or report.
Brief as a noun (usually, plural):

undershorts briefs.

Examples:

"I wear boxers under trousers but for sports I usually wear a brief."
Brief as a noun (obsolete):

A summary, précis or epitome; an abridgement or abstract.
Brief as a noun (UK, historical):

A letter patent, from proper authority, authorizing a collection or charitable contribution of money in churches, for any public or private purpose.
Brief as a noun:

(slang) A ticket of any type.

Brief as a verb (transitive):

To summarize a recent development to some person with decision-making power.

Examples:

"The U.S. president was briefed on the military coup and its implications on African stability."
Brief as a verb (transitive, legal):

To write a legal argument and submit it to a court.

Transient as an adjective:

Passing or disappearing with time; transitory.

Examples:

"a transient pleasure"
Transient as an adjective:

Remaining for only a brief time.

Examples:

"a transient view of a landscape"

"a transient disease"
Transient as an adjective (physics):

Decaying with time, especially exponentially.
Transient as an adjective (mathematics, stochastic processes, of a [[state]]):

having a positive probability of being left and never being visited again.
Transient as an adjective:

Occasional; isolated; one-off
Transient as an adjective:

Passing through; passing from one person to another.
Transient as an adjective (music):

Intermediate.
Transient as an adjective (philosophy):

Operating beyond itself; having an external effect.

Transient as a noun:

Something which is transient.
Transient as a noun (physics):

A transient phenomenon, especially an electric current; a very brief surge.
Transient as a noun (acoustics):

A relatively loud, non-repeating signal in an audio waveform which occurs very quickly, such as the attack of a snare drum.
Transient as a noun:

A person who passes through a place for a short time; a traveller; a migrant worker
Transient as a noun:

An unhoused person