pigeon keeping vs by-line

pigeon keeping and by-line both are nouns.

Word	Noun	Adjective	Verb	Adverb
pigeon keeping	Yes	No	No	No
by-line	Yes	No	No	No

As nouns, by-line is a hypernym of pigeon keeping; that is, by-line is a word with a broader meaning than pigeon keeping:

Other hypernyms of pigeon keeping include avocation, hobby, pursuit, sideline, spare-time activity.

pigeon keeping (noun)	by-line (noun)
the art and science of breeding domestic pigeons.	an auxiliary activity
	a line giving the name of the writer of a story or article