minibike vs moped

minibike and moped both are nouns.

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

minibike: 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

minibike (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