The difference between Cheek and Sass

When used as nouns, cheek means the soft skin on each side of the face, below the eyes, whereas sass means backtalk, cheek, sarcasm.

When used as verbs, cheek means to be impudent towards, whereas sass means to talk, to talk back.

check bellow for the other definitions of Cheek and Sass

Cheek as a noun (anatomy):

The soft skin on each side of the face, below the eyes; the outer surface of the sides of the oral cavity.
Cheek as a noun (anatomy, informal, usually, in the plural):

A buttock.
Cheek as a noun (informal, uncountable):

Impudence.

Examples:

"You’ve got some cheek, asking me for money!"
Cheek as a noun (biology, informal):

One of the genae, flat areas on the sides of a trilobite's cephalon.
Cheek as a noun:

One of the pieces of a machine, or of timber or stonework, that form corresponding sides or a similar pair.

Examples:

"the cheeks of a vice; the cheeks of a gun carriage"
Cheek as a noun (in plural):

The branches of a bridle bit.

Examples:

"rfquotek Knight"
Cheek as a noun (metalworking):

The middle section of a flask, made so that it can be moved laterally, to permit the removal of the pattern from the mould.

Cheek as a verb:

To be impudent towards.

Examples:

"Don't cheek me, you little rascal!"

Sass as a verb (US, informal, intransitive):

To talk, to talk back.
Sass as a verb (US, informal, transitive):

To speak insolently to.

Examples:

"Don't sass your teachers!"