motorcycle vs motorbike

motorcycle and motorbike both are nouns.

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

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

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

Other hyponyms of motorcycle include minibike, dirt bike, scrambler, trail bike.

As verbs, motorcycle and motorbike are synonyms defined as:

Other synonyms of motorcycle include cycle.

motorcycle (noun)	motorbike (noun)
a motor vehicle with two wheels and a strong frame	small motorcycle with a low frame and small wheels and elevated handlebars

motorcycle (verb)	motorbike (verb)
ride a motorcycle	ride a motorcycle