hobbyhorse vs rocking horse

hobbyhorse and rocking horse both are nouns.

Word	Noun	Adjective	Verb	Adverb
hobbyhorse	Yes	No	No	No
rocking horse	Yes	No	No	No

As nouns, hobbyhorse and rocking horse are synonyms defined as:

hobbyhorse and rocking horse: a child's plaything consisting of an imitation horse mounted on rockers; the child straddles it and pretends to ride

Other synonyms of hobbyhorse include hobby.

hobbyhorse (noun)	rocking horse (noun)
a child's plaything consisting of an imitation horse mounted on rockers; the child straddles it and pretends to ride	a child's plaything consisting of an imitation horse mounted on rockers; the child straddles it and pretends to ride
a topic to which one constantly reverts