robot bomb vs V-1

robot bomb and V-1 both are nouns.

Word	Noun	Adjective	Verb	Adverb
robot bomb	Yes	No	No	No
V-1	Yes	No	No	No

As nouns, robot bomb and V-1 are synonyms defined as:

robot bomb and V-1: a small jet-propelled winged missile that carries a bomb

Other synonyms of robot bomb include buzz bomb, doodlebug, flying bomb.

robot bomb (noun)	V-1 (noun)
a small jet-propelled winged missile that carries a bomb	a small jet-propelled winged missile that carries a bomb