male plug vs phone plug

male plug and phone plug both are nouns.

Word	Noun	Adjective	Verb	Adverb
male plug	Yes	No	No	No
phone plug	Yes	No	No	No

As nouns, phone plug is a hyponym of male plug; that is, phone plug is a word with a more specific, narrower meaning than male plug:

male plug: an electrical device with two or three pins that is inserted in a socket to make an electrical connection
phone plug: a plug for connecting a telephone

Other hyponyms of male plug include telephone plug.

male plug (noun)	phone plug (noun)
an electrical device with two or three pins that is inserted in a socket to make an electrical connection	a plug for connecting a telephone