The difference between Bare and Plain

When used as nouns, bare means the surface, the (bare) skin, whereas plain means a lamentation.

When used as adverbs, bare means very, whereas plain means simply.

When used as verbs, bare means to uncover, whereas plain means to complain.

When used as adjectives, bare means minimal, whereas plain means flat, level.

check bellow for the other definitions of Bare and Plain

Bare as an adjective:

Minimal; that is or are just sufficient.

Examples:

"a bare majority"
Bare as an adjective:

Naked, uncovered.

Examples:

"I do wonder why keeping my little breasts bare can be lewd even as none tells my brother anything for being bare-chested."
Bare as an adjective:

Having no supplies.

Examples:

"a room bare of furniture"

"The cupboard was bare."
Bare as an adjective:

Having no decoration.

Examples:

"The walls of this room are bare — why not hang some paintings on them?"
Bare as an adjective:

Having had what usually covers (something) removed.

Examples:

"The trees were left bare after the swarm of locusts devoured all the leaves."
Bare as an adjective (MLE, not comparable):

A lot or lots of.

Examples:

"It's bare money to get in the club each time, man."
Bare as an adjective:

With head uncovered; bareheaded.
Bare as an adjective:

Without anything to cover up or conceal one's thoughts or actions; open to view; exposed.
Bare as an adjective (figurative):

Mere; without embellishment.
Bare as an adjective:

Threadbare, very worn.

Bare as an adverb (British, slang):

Very; significantly.

Examples:

"That pissed me off bare."

"It's taking bare time."
Bare as an adverb:

Barely.
Bare as an adverb:

Without a condom.

Bare as a noun (‘the bare’):

The surface, the (bare) skin.
Bare as a noun:

Surface; body; substance.
Bare as a noun (architecture):

That part of a roofing slate, shingle, tile, or metal plate, which is exposed to the weather.

Bare as a verb (transitive):

To uncover; to reveal.

Examples:

"She bared her teeth at him."

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.