bike vs minibike

bike and minibike both are nouns.

Word	Noun	Adjective	Verb	Adverb
bike	Yes	No	Yes	No
minibike	Yes	No	No	No

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

bike: a motor vehicle with two wheels and a strong frame
minibike: small motorcycle with a low frame and small wheels and elevated handlebars

Other hyponyms of bike include motorbike, dirt bike, scrambler, trail bike.

bike (noun)	minibike (noun)
a wheeled vehicle that has two wheels and is moved by foot pedals	small motorcycle with a low frame and small wheels and elevated handlebars
a motor vehicle with two wheels and a strong frame

bike (verb)	minibike (verb)
ride a bicycle