saucer vs round shape

saucer and round shape both are nouns.

Word	Noun	Adjective	Verb	Adverb
saucer	Yes	No	No	No
round shape	Yes	No	No	No

As nouns, round shape is a hypernym of saucer; that is, round shape is a word with a broader meaning than saucer:

saucer (noun)	round shape (noun)
a small shallow dish for holding a cup at the table	a shape that is curved and without sharp angles
a disk used in throwing competitions
directional antenna consisting of a parabolic reflector for microwave or radio frequency radiation
something with a round shape resembling a flat circular plate