coverage vs extent

coverage and extent both are nouns.

Word	Noun	Adjective	Verb	Adverb
coverage	Yes	No	No	No
extent	Yes	No	No	No

As nouns, extent is a hypernym of coverage; that is, extent is a word with a broader meaning than coverage:

coverage (noun)	extent (noun)
the extent to which something is covered	the distance or area or volume over which something extends
the news as presented by reporters for newspapers or radio or television	the point or degree to which something extends
the total amount and type of insurance carried