guestroom vs bedchamber

guestroom and bedchamber both are nouns.

Word	Noun	Adjective	Verb	Adverb
guestroom	Yes	No	No	No
bedchamber	Yes	No	No	No

As nouns, bedchamber is a hypernym of guestroom; that is, bedchamber is a word with a broader meaning than guestroom:

Other hypernyms of guestroom include bedroom, chamber, sleeping accommodation, sleeping room.

guestroom (noun)	bedchamber (noun)
a bedroom that is kept for the use of guests	a room used primarily for sleeping