channel vs line of gab

channel and line of gab both are nouns.

Word	Noun	Adjective	Verb	Adverb
channel	Yes	No	Yes	No
line of gab	Yes	No	No	No

As nouns, line of gab is a hyponym of channel; that is, line of gab is a word with a more specific, narrower meaning than channel:

Other hyponyms of channel include back channel, lens, contact, inter-group communication, liaison, link, patter, spiel.

channel (noun)	line of gab (noun)
a way of selling a company's product either directly or via distributors	plausible glib talk (especially useful to a salesperson)
a passage for water (or other fluids) to flow through
a television station and its programs
a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance
a path over which electrical signals can pass
(often plural) a means of communication or access
a deep and relatively narrow body of water (as in a river or a harbor or a strait linking two larger bodies) that allows the best passage for vessels
a long narrow furrow cut either by a natural process (such as erosion) or by a tool (as e.g. a groove in a phonograph record)

channel (verb)	line of gab (verb)
send from one person or place to another
direct the flow of
transmit or serve as the medium for transmission