motorbike vs moped

motorbike and moped both are nouns.

Word	Noun	Adjective	Verb	Adverb
motorbike	Yes	No	Yes	No
moped	Yes	No	No	No

As nouns, moped is a hyponym of motorbike; that is, moped is a word with a more specific, narrower meaning than motorbike:

motorbike: small motorcycle with a low frame and small wheels and elevated handlebars
moped: a motorbike that can be pedaled or driven by a low-powered gasoline engine

motorbike (noun)	moped (noun)
small motorcycle with a low frame and small wheels and elevated handlebars	a motorbike that can be pedaled or driven by a low-powered gasoline engine

motorbike (verb)	moped (verb)
ride a motorcycle