moped vs minibike

moped and minibike both are nouns.

As nouns, minibike is a hypernym of moped; that is, minibike is a word with a broader meaning than moped:

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

Other hypernyms of moped include motorbike.

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