coaster vs protective covering

coaster and protective covering both are nouns.

Word	Noun	Adjective	Verb	Adverb
coaster	Yes	No	No	No
protective covering	Yes	No	No	No

As nouns, protective covering is a hypernym of coaster; that is, protective covering is a word with a broader meaning than coaster:

coaster: a covering (plate or mat) that protects the surface of a table (i.e., from the condensation on a cold glass or bottle)
protective covering: a covering that is intend to protect from damage or injury

Other hypernyms of coaster include protection, protective cover.

coaster (noun)	protective covering (noun)
a covering (plate or mat) that protects the surface of a table (i.e., from the condensation on a cold glass or bottle)	the tough natural covering of some organisms
someone who coasts	a covering that is intend to protect from damage or injury
a resident of a coastal area