gas line vs pipeline

gas line and pipeline both are nouns.

Word	Noun	Adjective	Verb	Adverb
gas line	Yes	No	No	No
pipeline	Yes	No	No	No

As nouns, pipeline is a hypernym of gas line; that is, pipeline is a word with a broader meaning than gas line:

Other hypernyms of gas line include line.

gas line (noun)	pipeline (noun)
a pipeline used to transport natural gas	a pipe used to transport liquids or gases
a pipe that carries gasoline from a tank to a gasoline engine	gossip spread by spoken communication
a queue of vehicles waiting to purchase gasoline