pecker vs penis

pecker and penis both are nouns.

Word	Noun	Adjective	Verb	Adverb
pecker	Yes	No	No	No
penis	Yes	No	No	No

As nouns, penis is a hypernym of pecker; that is, penis is a word with a broader meaning than pecker:

Other hypernyms of pecker include member, phallus.

pecker (noun)	penis (noun)
bird with strong claws and a stiff tail adapted for climbing and a hard chisel-like bill for boring into wood for insects	the male sex organ
horny projecting mouth of a bird
obscene terms for penis