The difference between Passing and Transient

When used as nouns, passing means death, dying, whereas transient means something which is transient.

When used as adjectives, passing means that passes away, whereas transient means passing or disappearing with time.

Passing is also adverb with the meaning: surpassingly, greatly.

check bellow for the other definitions of Passing and Transient

Passing as an adjective:

That passes away; ephemeral.
Passing as an adjective (now, _, rare, literary):

Pre-eminent, excellent, extreme.
Passing as an adjective:

Vague, cursory.
Passing as an adjective:

Going past.

Examples:

"passing cars"

Passing as an adverb (now, _, literary, _, or, _, archaic):

Surpassingly, greatly.

Passing as a noun:

Death, dying; the end of something.
Passing as a noun:

The fact of going past; a movement from one place to another or a change from one state to another.
Passing as a noun (legal):

The act of approving a bill etc.
Passing as a noun (sports):

The act of passing a ball etc. to another player.
Passing as a noun:

A form of juggling where several people pass props between each other, usually clubs or rings.
Passing as a noun (sociology):

The ability of a person to be regarded as a member of an identity group or category different from their own.

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