Main Difference
The main difference between Smirk and Smile is that the Smirk is a facial expression and Smile is a conscious or subconscious facial muscular movement conveying mirth or pleasure.
Smirk
A smirk is a smile evoking insolence, scorn, or offensive smugness, falling into the category of what Desmond Morris described as Deformed-compliment Signals.A smirk may also be an affected, ingratiating smile, as in Mr Bennet’s description of Mr Wickham as making smirking love to all his new in-laws in the novel Pride and Prejudice.
Smile
A smile is a facial expression formed primarily by flexing the muscles at the sides of the mouth. Some smiles include a contraction of the muscles at the corner of the eyes, an action known as a “Duchenne smile”. Smiles performed without the eye contraction may be perceived as insincere.
Among humans, smiling is an expression denoting pleasure, sociability, happiness, joy or amusement. It is distinct from a similar but usually involuntary expression of anxiety known as a grimace. Although cross-cultural studies have shown that smiling is a means of communication throughout the world, there are large differences among different cultures, with some using smiles to convey confusion or embarrassment.
Smirk (noun)
an uneven, often crooked smile that is insolent, self-satisfied or scornful
Smirk (noun)
a forced or affected smile; a simper
Smirk (verb)
To smile in a way that is affected, smug, insolent or contemptuous.
Smirk (adjective)
smart; spruce; affected; simpering
Smile (noun)
A facial teeth, without vocalisation, and in humans is a common involuntary or voluntary expression of happiness, pleasure, amusement or anxiety.
“She’s got a perfect smile.”
“He has a sinister smile.”
“She had a smile on her face.”
“He always puts a smile on my face.”
Smile (verb)
To have (a smile) on one’s face.
“When you smile, the whole world smiles with you.”
“I don’t know what he’s smiling about.”
“She smiles a beautiful smile.”
Smile (verb)
To express by smiling.
“to smile consent, or a welcome”
Smile (verb)
To express amusement, pleasure, or love and kindness.
Smile (verb)
To look cheerful and joyous; to have an appearance suited to excite joy.
“The sun smiled down from a clear summer sky.”
Smile (verb)
To be propitious or favourable; to countenance.
“The gods smiled on his labours.”
Smirk (verb)
smile in an irritatingly smug, conceited, or silly way
“he smirked in triumph”
Smirk (noun)
a smug, conceited, or silly smile
“Gloria pursed her mouth in a self-satisfied smirk”