The difference between Boy and Knave

When used as nouns, boy means a male child or teenager, as distinguished from infants or adults, whereas knave means a boy.

Boy is also interjection with the meaning: exclamation of surprise, pleasure or longing.

Boy is also verb with the meaning: to use the word boy to refer to someone.

check bellow for the other definitions of Boy and Knave

Boy as a noun:

A young male, particularly A male child or teenager, as distinguished from infants or adults.

Examples:

"Kate is dating a boy named Jim."
Boy as a noun (diminutive):

A male child: a son of any age.
Boy as a noun (affectionate, diminutive):

A male of any age, particularly one rather younger than the speaker.
Boy as a noun (obsolete):

A male of low station, (especially as pejorative) a worthless male, a wretch; a mean and dishonest male, a knave.
Boy as a noun (now, rare, and, usually, offensive, _, outside some Commonwealth nations):

A male servant, slave, assistant, or employee, particularly: A younger such worker. A non-white male servant regardless of age, particularly as a form of address. A male camp follower.
Boy as a noun (now, offensive):

Any non-white male, regardless of age.
Boy as a noun:

A male animal, especially, in affectionate address, a male dog.

Examples:

"C'mere, boy! Good boy! Who's a good boy?"

"Are you getting a boy cat or a girl cat?"
Boy as a noun (historical, military):

A former low rank of various armed services; a holder of this rank.
Boy as a noun (US, slang):

Heroin.

Boy as a verb:

to use the word boy to refer to someone

Examples:

"Don't boy me!"
Boy as a verb (transitive):

to act as a boy

Knave as a noun (archaic):

A boy; especially, a boy servant.
Knave as a noun (archaic):

Any male servant; a menial.
Knave as a noun:

A tricky, deceitful fellow; a dishonest person.

Examples:

"synonyms: rogue villain"
Knave as a noun (cards):

A playing card marked with the figure of a servant or soldier; a jack.