The difference between Plain and Quiet

When used as nouns, plain means a lamentation, whereas quiet means the absence of sound.

When used as verbs, plain means to complain, whereas quiet means to become quiet, silent, still, tranquil, calm.

When used as adjectives, plain means flat, level, whereas quiet means with little or no sound.

Plain is also adverb with the meaning: simply.

Quiet is also interjection with the meaning: be quiet.

check bellow for the other definitions of Plain and Quiet

Plain as an adjective (now, _, rare, regional):

Flat, level.
Plain as an adjective (of food):

Simple. Ordinary; lacking adornment or ornamentation; unembellished. Of just one colour; lacking a pattern. Simple in habits or qualities; unsophisticated, not exceptional, ordinary. Having only few ingredients, or no additional ingredients or seasonings; not elaborate, without toppings or extras. Containing no extended or nonprinting characters (especially in ).

Examples:

"He was dressed simply in plain black clothes."

"a plain tune"

"a plain pink polycotton skirt"

"They're just plain people like you or me."

"Would you like a poppy bagel or a plain bagel?"
Plain as an adjective:

Obvious. Evident to one's senses or reason; manifest, clear, unmistakable. Downright; total, unmistakable (as intensifier).

Examples:

"His answer was just plain nonsense."
Plain as an adjective:

Open. Honest and without deception; candid, open; blunt. Clear; unencumbered; equal; fair.

Examples:

"Let me be plain with you: I don't like her."
Plain as an adjective:

Not unusually beautiful; unattractive.

Examples:

"Throughout high school she worried that she had a rather plain face."

Plain as an adverb (colloquial):

Simply

Examples:

"It was just plain stupid."

"I plain forgot."

Plain as a verb (reflexive, obsolete):

To complain.
Plain as a verb (ambitransitive, now, rare, poetic):

To lament, bewail.

Examples:

"to plain a loss"

"rfquotek Sir J. Harrington"

Plain as a verb (obsolete, transitive):

To level; to raze; to make plain or even on the surface.
Plain as a verb (obsolete, transitive):

To make plain or manifest; to explain.

Quiet as an adjective:

With little or no sound; free of disturbing noise.

Examples:

"I can't hear the music; it is too quiet."
Quiet as an adjective:

Having little motion or activity; calm.

Examples:

"the sea was quiet'"

"a quiet night at home"

"all quiet on the Western front"
Quiet as an adjective:

Not busy, of low quantity.

Examples:

"The traffic was quiet for a Monday morning."

"Business was quiet for the season."
Quiet as an adjective:

Not talking much or not talking loudly; reserved.

Examples:

"He's a very quiet man usually, but is very chatty after a few beers."
Quiet as an adjective:

Not showy; undemonstrative.

Examples:

"a quiet dress"

"'quiet colours"

"a quiet movement"
Quiet as an adjective (software):

Requiring little or no interaction.

Examples:

"a quiet install"

Quiet as a verb:

To become quiet, silent, still, tranquil, calm.

Examples:

"When you quiet, we can start talking."
Quiet as a verb:

To cause someone to become quiet.

Examples:

"Can you quiet your child? He's making lots of noise."

"The umpire quieted the crowd, so the game could continue in peace."

Quiet as a noun:

The absence of sound; quietness.

Examples:

"There was a strange quiet in the normally very lively plaza."

"We need a bit of quiet before we can start the show."
Quiet as a noun:

the absence of movement; stillness, tranquility