cylinder vs round shape

cylinder and round shape both are nouns.

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

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

cylinder: a surface generated by rotating a parallel line around a fixed line
round shape: a shape that is curved and without sharp angles

cylinder (noun)	round shape (noun)
a cylindrical container for oxygen or compressed air	a shape that is curved and without sharp angles
a chamber within which piston moves
a surface generated by rotating a parallel line around a fixed line
a solid bounded by a cylindrical surface and two parallel planes (the bases)